Method and system for manufacturing a powder

Abstract

The present invention relates to a powder for use in an additive manufacturing process, wherein the powder comprises a processed plurality of particles, wherein each of the processed plurality of particles comprises a particle, wherein a surface of the particle comprises, at least in part, a substantially curved face, and wherein a ratio of a surface area of the substantially curved face to a total surface area of the particle is less than 1, preferably less than 0.95, further preferably less than 0.9. The present invention also relates to a system and a method for manufacturing the powder and to a use of the powder in an additive manufacturing process.

Description

[0001] Method and System for manufacturing a Powder

[0002] Field

[0003] The present invention relates generally to the field of manufacturing processes. More particularly, it relates to a powder for use in an additive manufacturing process, and to a method and system for producing the powder.

[0004] Background

[0005] Additive manufacturing processes provide a novel approach to manufacturing. Typically, in an additive manufacturing process, a three-dimensional object is manufactured in layers. One common technique for additive manufacturing comprises a sintering process, in particular a laser sintering process. In a laser sintering process, for each layer to be manufactured, a powder is spread over a plane comprising the last layer, and a laser is used to trace out the layer to be manufactured. As a result of irradiation with the laser, particles in the powder melt and fuse, thus forming the next layer. The above steps are repeated for each layer until the object has been created.

[0006] The powder that is used may need to comprise certain characteristics in order to be used for manufacturing an object as described above. Particularly advantageous characteristics are well-known to the skilled person and may be found, for example, in Schmid, Laser Sintering with Plastics: Technology, Processes, and Materials.

[0007] For example, the powder may be required to have a suitable melting point to allow melting under action of the laser. Further, the powder may need to have suitable flow characteristics to allow a uniform layer to be created before sintering with the laser. Yet further, particles in the powder may be desired to have a size in a defined range or, at least substantially, a defined shape.

[0008] EP3394155B1 describes a powder for use in an additive manufacturing process comprising generally cylindrical particles, the particles having a defined size distribution. The generally cylindrical particles are produced by cutting an aggregated polymeric based tow comprising multiple filaments, the size of the particles being defined by, inter alia, a feed rate of the filament and the cutting interval. A relevant consideration in producing the powder using the method may be the overall throughput of the process, i.e., the rate at which particles are produced by the process. In particular, as the process may require the production of the aggregated polymeric based tow and cutting the relatively thick tow with a blade, the cutting process may be time-consuming. Additionally, due to the large number of filaments being cut at a time, the blade may lose its sharpness relatively quickly.

[0009] Wulfhorst et. al. (2011) describes a method for producing particles by cutting a filament. However, the particles produced may have a size larger than a size typically used for laser sintering. Summary

[0010] In light of the above, it is an object of the present invention to provide a technology that may overcome, or at least alleviate, the shortcomings of the prior art. Embodiments of the present technology may allow production of a powder suitable for additive manufacturing processes with particles of size in the defined range for additive manufacturing that may be more efficient, allowing a higher throughput, and that may be more robust against degradation of components, such as a blade, used in the process.

[0011] It is also an object of the present invention to provide a powder that may be used in an additive manufacturing process that may exhibit improved characteristics of relevance to the process, as described above. For example, the powder, as described herein, may exhibit improved flow characteristics, with respect to the prior art.

[0012] In the following, a majority may be understood to comprise at least 50%. Further, in the following, a melting process has been described. However, it may be understood that embodiments of the present invention may also encompass a sintering process, wherein a temperature of the process is kept below a melting point of a pre-cursor particle. Thus, whenever reference is herein made to melting, sintering may be understood to be equivalently applicable, unless explicitly or otherwise stated.

[0013] According to a first aspect, the present invention relates to a method for manufacturing a powder for use in an additive manufacturing process, wherein the powder comprises a plurality of particles, and wherein the method comprises producing each of a processed plurality of the plurality of particles from each of a plurality of pre-cursor particles. In other words, embodiments of the present invention relate to manufacture of a powder that may be used, for example, in a laser sintering process. The powder may, generally, comprise one or more types of constituent particles. It is an aspect of the present invention to manufacture at least some of the constituent particles of the powder. As described above, the macroscopic properties of the powder that are relevant to additive manufacturing may depend on the microscopic properties of the constituent particles of the powder. Thus, for example, as further described below, a shape and size of the constituent particles may determine whether or not the powder exhibits good flow properties.

[0014] The processed plurality of particles may be understood to comprise a subset of the set of particles that may be produced as described herein.

[0015] Producing each of the processed plurality of particles may comprise melting or sintering, at least in part, each of the plurality of pre-cursor particles. As a result of melting or sintering, the pre-cursor particle may shrink along a dimension of maximum extension, while it may expand along the other dimensions as the mass may be preserved. The resultant shape may be of particular advantage in achieving desirable macroscopic properties of the powder comprising the processed plurality of particles. In particular, a flow behavior of the powder may be improved. The method may comprise arranging each of the plurality of pre-cursor particles on a substantially flat surface before melting. As a result of their arrangement on the substantially flat surface before melting, the pre-cursor particles, after melting or sintering, may comprise a substantially flat face. The skilled person appreciates that a roughness of the substantially flat face may correspond to a roughness of the substantially flat face on which the pre-cursor particles are arranged before melting.

[0016] The method may comprise producing any, preferably each, of the plurality of pre-cursor particles. In other words, some or even none of the plurality of pre-cursor particles may be produced as described herein, but may be acquired differently. Preferably, however, some, preferably a majority, further preferably each, of the plurality of pre-cursor particles may be produced as described herein. Embodiments of the present technology may allow greater control over the size and shape of the pre-cursor particles, thus, allowing better reproducibility in the properties of the powder.

[0017] Each of the plurality of pre-cursor particles may comprise a section of a filament.

[0018] The method may comprise cutting the filament. Cutting the filament may result in a section of the filament. The section may correspond to the pre-cursor particle, or may be further processed to produce the pre-cursor particle. The skilled person understands that multiple cuts of the filament may result in multiple sections of the filament, each of the multiple sections being or leading to a pre-cursor particle.

[0019] Cutting the filament may comprise guiding the filament through a channel, the channel defined by a feed end, corresponding to an end from which the filament enters the channel, and a cutting end, corresponding to an end out of which the filament exits the channel.

[0020] The method may comprise cutting a section of the filament extending out of the channel at the cutting end. In other words, the cutting of the filament may be carried out at one end of the channel.

[0021] The method may comprise cutting the filament with a blade.

[0022] Cutting the filament may comprise sliding the blade over the cutting end.

[0023] The method may comprise sliding the blade over the cutting end periodically with a cutting frequency.

[0024] The method may comprise guiding the filament through the channel at a guiding speed.

[0025] The method may comprise guiding the filament through the channel in a guiding direction.

[0026] An extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction may be based, at least in part, on the cutting frequency. An extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction may be based, at least in part, on the guiding speed.

[0027] The method may comprise choosing the guiding speed based, at least in part, on a desired extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0028] The method may comprise choosing the cutting frequency based, at least in part, on a desired extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction. Thus, by changing the cutting frequency, an extension of the cut section may be changed, as long as a speed at which the filament is guided through the channel is kept constant. Alternatively, or additionally, the extension of the cut section may be changed by changing the guiding speed. In some embodiments, the guiding speed may be limited by a laminarity of flow of a fluid that may be used to guide the filament along the channel. In such embodiments, the cutting frequency may be varied to change the extension of the cut section.

[0029] The method may comprise producing a cut plurality of the plurality of pre-cursor particles. The cut plurality of the plurality of pre-cursor particles may be understood to comprise a subset of the set of pre-cursor particles that may be cut from filaments as described herein.

[0030] Producing the cut plurality of the plurality of pre-cursor particles may comprise cutting a plurality of filaments.

[0031] Cutting the plurality of filaments may comprise guiding the plurality of filaments through the channel.

[0032] Cutting the plurality of filaments may comprise guiding a first guided plurality of the plurality of filaments through a first channel and a second guided plurality of the plurality of filaments through a second channel, wherein each of the first and the second channels is defined by a feed end, corresponding to an end from which the first and second guided plurality of filaments enters the channel, and a cutting end, corresponding to an end out of which the first and second guided plurality of filaments exits the channel respectively. That is, some filaments may be guided through one channel and some other filaments may be guided through another channel. In some embodiments, the feed ends and / or the cutting ends of both the first and the second channels may lie in the same plane. It may be of particular advantage to position at least the cutting ends of both the first and the second channels in the same plane to allow the blade to slide over the plane and cut the first and second guided pluralities in one stroke.

[0033] The method may comprise twisting a bundled plurality of the plurality of filaments together into a filament bundle. That is, some filaments may be bundled together and these filaments may be referred to as a bundled plurality. Twisting the bundled plurality of filaments together may be advantageous in allowing easier control, and thus guiding through the channel, of the bundled plurality as the plurality of filaments within a bundle may push against each other. Further, the bundled plurality may be more resistant to bending under the action of the blade.

[0034] The method may comprise twisting a first bundled plurality of the plurality of filaments together into a first filament bundle.

[0035] The method may comprise twisting a second bundled plurality of the plurality of filaments together into a second filament bundle.

[0036] The method may comprise combining the first and the second filament bundles. Twisting together filament bundles may further enhance the ability to control the plurality of filaments and resistance to bending under action of the blade.

[0037] The method may comprise twisting together the bundled plurality of the plurality of the filaments before cutting.

[0038] A diameter of any one of the plurality of filaments is, at least significantly, identical to a diameter of any other of the plurality of filaments. At least significantly identical diameters may be of advantage in producing a more uniform distribution of pre-cursor particles, that may result in a more uniform distribution of the processed plurality of particles.

[0039] A diameter of a first of the plurality of filaments is different from a diameter of a second of the plurality of filaments.

[0040] Guiding through the channel(s) may comprise guiding by means, at least in part, of a fluid flow.

[0041] The fluid may comprise any of air, an inert gas, or nitrogen. Generally, it may be of advantage to use, as the fluid, a gas that has a relatively low concentration of oxygen to lower a risk of creating a potentially explosive mixture of the powder and oxygen. In particular, "relatively low" may be understood to comprise a concentration lower than a limiting oxygen concentration corresponding, as understood by the skilled person, to a concentration below which combustion is not possible. The skilled person appreciates that the specific value of the concentration may vary depending on the material of the filament(s).

[0042] The method may further comprise reducing a turbulence of the fluid flow. Reduction in turbulence may be determined, for example, visually by determining that the filaments are moving in a defined manner consistent with a low-turbulence fluid flow. Generally, a laminar flow of the fluid may be even better for the process reproducibility but it may be difficult to achieve a laminar flow at mass production level.

[0043] Alternatively, or additionally, a sensor may be installed to measure a flow rate of the fluid. Combined with, inter alia, measurements of a channel's dimensions, or a fraction of the channel's volume occupied by filaments (that may be referred to as an occupancy fraction), the flow rate may allow characterization of a laminarity of the flow using well-known ratios, such as the Reynolds number. Yet further alternatively, or additionally, the laminarity of the fluid flow may be characterized simply by values of the flow rate, the occupancy fraction, or dimensions of the channel. Yet further alternatively, or additionally, an image sensor may be installed to capture an image and / or a video of the channel. Any suitable image processing algorithms such as a neural network may then be employed to determine if the flow of the fluid is turbulent.

[0044] Guiding through a channel may comprise guiding by means, at least in part, of an electrostatic field.

[0045] Guiding through the channel(s) may comprise establishing a lower pressure at the cutting end than at the feed end. In other words, the filament(s) may be "sucked into" the channel. Use of a lower pressure at the cutting end may reduce a volume of fluid needed to guide the filament(s) through the channels and may allow for better reproducibility of the process.

[0046] The method may comprise maintaining a temperature of the blade below a pre-defined threshold. In particular, the blade may have to be maintained at a temperature below a melting point of the filament(s) so that a probability of a clean cut is enhanced.

[0047] The method may comprise cooling the blade. As the blade is used to cut multiple filaments, the blade may heat up over time. Therefore, it may be of advantage to cool the blade.

[0048] The method may comprise pumping a thermal fluid over a heated element, the heated element in thermal contact with the blade. A thermal fluid may be understood to comprise any fluid that may absorb heat from the heated element. For example, the thermal fluid may comprise water at a lower temperature than the heated element. Alternatively, or additionally, the thermal fluid may comprise a fluid that may be vaporized on absorption of heat from the heated element.

[0049] The heated element may be understood to comprise any element that may absorb heat from the blade. In particular, thermal contact may be understood to comprise heat transfer between the blade and the heated element. As may be appreciated, the direction and efficiency of heat transfer may depend, at least in part, on the temperature difference between the heated element and the blade and also on the material of the blade and the heated element.

[0050] For example, the heated element may comprise a die through which one or more channels may be bored for guiding the filament(s) as described above. The thermal fluid may then be pumped as close as possible to the cutting plane of the die. The die, or at least a part thereof close to the cutting plane, may then be made of a material with a high thermal conductivity, such as a metal. For example, cooling channels may also be bored through the die, that may be closed at the cutting end, such that the thermal fluid may be pumped through the cooling channels. The thermal fluid may be pumped to a cold element such that heat may flow from the thermal fluid to the cold element. Thus, a cyclical flow of the thermal fluid between the heated and cold elements may be realized.

[0051] The method may comprise blowing, over the blade, a gas with a temperature, at least significantly, lower than a temperature of the blade.

[0052] The method may comprise cooling the fluid as described above. That is, the fluid used to guide the filament(s) through the channel may be cooled. Thus, a temperature at the cutting end may be, at least significantly, reduced, allowing the temperature of the blade to be reduced.

[0053] The method may comprise cooling the filament and / or any of the plurality of filaments before cutting.

[0054] Thus, various methods as described above, or any combination thereof, may be used to cool the blade. The choice of any particular method or combination may be based, for example, on an ease and efficiency of implementing the method. For example, the use of a thermal fluid may be more efficient, but cooling using a thermal fluid may be more difficult to implement.

[0055] The filament and / or any of the plurality of filaments may comprise a partially or fully drawn yarn, and the method may comprise heating the cut section(s) of the filament and / or of any of the plurality of filaments.

[0056] The method may comprise heating to a temperature lower than a melting point of the filament and / or of any of the plurality of filaments. In other words, the pre-cursor particle(s) may be produced by heating the cut section(s) of the filament and or of any of the plurality of filaments. This may be of particular relevance as shorter lengths of the precursor particle(s) may be produced. For example, typically, only a length of the cut section of ~ 100 pm may be minimally realized. In order to produce a smaller cut section, further processing may be required. By heating a partially or fully drawn yarn, shrinking of the cut section may be effected, thus reducing the length of the cut section even further. The skilled person understands that a temperature to which the cut section(s) are heated to shrink may be lower than a temperature at which sintering of the pre-cursor particle(s) is carried out.

[0057] A result of the heating is a decrease in an extension of the cut section(s) in at least one direction.

[0058] Melting may comprise passing each of the plurality of pre-cursor particles through a furnace.

[0059] The method may comprise dispersing the plurality of pre-cursor particles on a conveyor belt passing through the furnace. A temperature of the furnace may be greater than a melting point of any of the plurality of pre-cursor particles. In some embodiments, however, a lower temperature may also be used. For example, the pre-cursor particles, as described above, may be produced by melt spinning (especially when made from fully drawn yarn) or any other process which causes them to have a significant orientation of the molecular chains in the direction of filament elongation. Such a material may be heated above its glass transition temperature, but below its melting temperature, to produce at least one of the processed plurality of particles. In particular, heating above the glass transition temperature may change the orientation of the molecules resulting in a shape change such that a length of a particle is decreased and a diameter is increased.

[0060] For example, the pre-cursor particles (or, equivalently, the filament(s)) may comprise a polypropylene material which shows a melting peak in the DSC-curve of 155°C. Decomposition according to TGA-curve starts above 300°C. Then, the furnace may be set to a temperature of about 200°C.

[0061] At least one of the plurality of pre-cursor particles may comprise a polymer. The temperature of the furnace may be less than a decomposition temperature of the at least one particle. The decomposition temperature may be understood to be the temperature at which the polymer chain starts breaking.

[0062] Each of a polymeric plurality of the plurality of pre-cursor particles may comprise a polymer, and the temperature of the furnace may be less than a decomposition temperature of any of the polymeric plurality of pre-cursor particles.

[0063] The method may comprise cooling each of the plurality of pre-cursor particles after passing them through the furnace to obtain each of the processed plurality of particles.

[0064] The method may comprise cooling for a duration defined by the range 0 - Is, preferably by 1 - 5s, further preferably by 5 - 20s, yet further preferably by 20 - 60s, even more preferably greater than 60s. Cooling may be effected to a temperature lower than a crystallization temperature of a pre-cursor particle. For example, the crystallization temperature for a polypropylene 122°C. Thus, pre-cursor particles that comprise polypropylene may be cooled to a temperature lower than 122°C. Typically, cooling may be effected to a temperature in the range defined by 40 and 80°C, preferably 45 and 80°C, further preferably by 50 and 80°C.

[0065] A result of melting, at least in part, each of the plurality of pre-cursor particles may be an increase in a degree of crystallinity of each of the plurality of pre-cursor particles.

[0066] The increase in a degree of crystallinity may be at least 5 % for at least 30 % of the plurality of pre-cursor particles. At least one, preferably a plurality, further preferably each, of the processed plurality of particles may comprise a polymer. In particular, if the pre-cursor particle comprises a polymer, the corresponding particle of the processed plurality of particles may comprise the, at least significantly, same polymer.

[0067] The polymer may comprise a thermoplastic polymer.

[0068] Dispersing the plurality of pre-cursor particles may comprise sieving the plurality of precursor particles.

[0069] Sieving the plurality of pre-cursor particles may comprise realizing a desired areal number density of the plurality of pre-cursor particles on the conveyor belt.

[0070] The desired areal number density may be based, at least in part, on a speed of the conveyor belt.

[0071] The desired areal number density may be based, at least in part, on a size of the sieve.

[0072] The desired areal number density may be based, at least in part, on a throughput of the sieve.

[0073] The desired areal number density may be chosen so as to reduce agglomeration of precursor particles during melting, resulting in an increase in the number of large particles. Sieving the plurality of pre-cursor particles may be of particular advantage as a size of the sieve (or the holes thereof) may be chosen so as to separate particles of size larger than the size of the sieve. By appropriately choosing the size of the sieve, smaller (for example, less than about 5 pm) pre-cursor particles may be positioned close together on the conveyor belt, whereas larger particles may be positioned distantly. As a result of the subsequent melting, or sintering, the smaller particles may agglomerate, thus reducing the number of smaller particles. Reducing the number of smaller particles may be of advantage in improving flow properties of the powder as known to the skilled person.

[0074] According to a second aspect, the present invention relates to a particle, wherein a surface of the particle comprises, at least in part, a substantially curved face. A substantially curved face may be understood to comprise a face that comprises a macroscopic curvature. The skilled person understands that a surface of the particle may comprise a roughness associated with the manufacturing process, such that the surface may be considered as comprising protrusions (or small curves). However, the skilled person understands that, when smoothed over an appropriate scale, the surface may comprise a different shape. Embodiments of the present invention particularly relate to a particle for which this different shape comprises a curved face.

[0075] A ratio of a surface area of the substantially curved face to a total surface area of the particle may be less than 1, preferably less than 0.95, further preferably less than 0.9. For example, a minimum value of the ratio is 0.5 for a spherical cap in the limit of a zero angle. A ratio of a surface area of the substantially curved face to a total surface area of the particle may be at least as large as 0.25, preferably at least as large as 0.30, further preferably at least as large as 0.35.

[0076] The substantially curved face, or at least a part thereof, may comprise a significantly finite radius of curvature in at least two dimensions. Significantly finite may be understood to comprise a value that is significantly different from both zero and infinity. In particular, the substantially curved face may be curved in at least, preferably exactly, two dimensions, such as the surface of a sphere or an ellipsoid as compared, for example, to the surface of a cylinder that is curved in exactly one dimension. The curvature in two dimensions may allow for improved flow properties of a powder comprising particle(s) as described herein.

[0077] A defined fraction of the substantially curved face may comprise the significantly finite radius of curvature in at least two dimensions, wherein the defined fraction may be at least as large as 0.3, preferably at least as large as 0.4, further preferable at least as large as 0.5. The fraction may be defined by comparing, for example, a surface area of the curved face, at each point of which the radius of curvature is significantly finite in at least two dimensions, with a total surface area of the curved face.

[0078] The particle may comprise a substantially flat face.

[0079] A maximum extension of the particle in any dimension may be 500 pm, preferably 400 pm, further preferably 300 pm, yet further preferably 200 pm, even more preferably 100 pm, even more preferably 50 pm.

[0080] A maximum extension of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face may be 300 pm, preferably 200 pm, further preferably 100 pm, even more preferably 50 pm.

[0081] A maximum extension of the particle in a plane, at least significantly, parallel to the substantially flat face may be 500 pm, preferably 400 pm, further preferably 300 pm, yet further preferably 200 pm, even more preferably 100 pm, even more preferably 50 pm.

[0082] A ratio of a maximum extension of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particle in a plane, at least significantly, parallel to the substantially flat face may be less than 0.7, preferably less than 0.6, further preferably less than 0.5, even more preferably less than 0.4.

[0083] The curved face may define a boundary of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face.

[0084] The particle may comprise, generally, the shape of a frustum of a sphere. Generally comprising the shape of a frustum of a sphere may be understood as the particle fitting within a best-fit frustum of a sphere while occupying at least a majority, i.e., at least 50%, of an interior volume of the best-fit frustum of a sphere. For example, the particle may occupy at least 60%, preferably at least 65%, further preferably at least 70%, of the interior volume of the best-fit frustum of a sphere.

[0085] A cross-section of the particle in a plane, at least substantially, parallel to the substantially flat may be generally elliptical. Generally elliptical may be understood as the cross-section fitting within a best-fit ellipse while occupying at least a majority, i.e., at least 50%, of an interior area of the best-fit ellipse. For example, the cross-section may occupy at least 60%, preferably at least 65%, further preferably at least 70%, of the interior area of the best-fit ellipse.

[0086] The particle may comprise a generally cylindrical shape.

[0087] A ratio of a maximum length and a maximum width of the particle may be less than 0.7, preferably less than 0.6, further preferably less than 0.5, even more preferably less than 0.4. The maximum length may be understood to correspond to a maximum extension of the particle along a straight line in any direction. The maximum width may be understood to correspond to a maximum extension of the particle along a straight line lying in a plane perpendicular to a direction of the maximum length. For example, for a cylindrical particle, the maximum width may correspond to a diameter of the cylinder.

[0088] The particle may comprise a unitary construction.

[0089] The particle may comprise a non-unitary construction.

[0090] The particle may comprise a cut artifact.

[0091] A volume of the particle may be less than 1.4 x 107pm3, preferably less than 4.2 x 106pm3, further preferably less than 5.2 x 105pm3.

[0092] The particle may comprise at least one chemical compound.

[0093] The particle may comprise a plurality of chemical compounds.

[0094] At least one of the at least one or plurality of chemical compound(s) may comprise one of a polyamide, a polyethylene, a polypropylene, a polyetherketone, a polyoxymethylene acetal, a polytetrafluoroethylene, a polypheneylene sulfide, a polybutylene terephthalate, an aliphatic nylon polyamide, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 10, nylon 10-10, nylon 10-12, nylon 11, nylon 12, a low-density polyethylene, a medium-density polyethylene, or a high-density polyethylene.

[0095] The particle may comprise any of a semi-crystalline or amorphous material-based polymer. The method as described above, wherein each of the processed plurality of particles may comprise a particle as described above.

[0096] According to a third aspect, the present invention relates to a powder for use in an additive manufacturing process, wherein the powder is manufactured by a method as described above.

[0097] According to a fourth aspect, the present invention relates to a powder for use in an additive manufacturing process, wherein the powder comprises a processed plurality of particles, wherein at least one of the processed plurality of particles comprises a particle as described above.

[0098] Each of the processed plurality of particles may comprise a particle according to any of the preceding particle embodiments.

[0099] The processed plurality of particles may constitute a majority of the plurality of particles. A majority, as used in this document, may be understood to comprise at least 50 %. Thus, each of at least 50% by number of the plurality of particles may comprise a particle as described above.

[0100] The processed plurality of particles may comprise a majority by weight of the plurality of particles.

[0101] The processed plurality of particles may comprise a majority by volume of the plurality of particles.

[0102] The processed plurality of particles may define a volume distribution representing a distribution of the total volume of the processed plurality and / or of the powder with a size of the particles. Defining a distribution, as used herein, may be understood to imply the plurality of particles having a size, shape, or other property that is distributed according to the distribution. Thus, the processed plurality of particles defining a volume distribution representing a distribution of the total volume of the processed plurality and / or of the powder with a size of the particles may be understood to indicate a fraction of the total volume of the processed plurality and / or the powder occupied by particles of a defined size.

[0103] Each of the processed plurality of particles may comprise a particle as described above, and the processed plurality of particles may define a number distribution representing a distribution of the total number of particles in the processed plurality and / or in the powder with a size of the particles. The volume and number distribution of the particles may typically be obtained using laser diffraction or a dynamic image analysis (as performed, for example, by the SYNC analyzer, described at https: / / www.microtrac.com / products / particle-size-shape-analysis / laser- diffraction / sync / ). It may, thus, be understood that the size of the particles determined in such a system may be a size proportional to an effective cross-sectional area of a particle parallel to a wavefront of the laser or an analyzing beam. Thus, the size may depend, inter alia, on an orientation of the particle relative to the laser or analyzing beam.

[0104] Each of the processed plurality of particles may comprise a particle as described above, and the processed plurality of particles may define a volumetric relative size distribution representing a distribution of the total volume of the processed plurality and / or of the powder with a ratio of a maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face. In other words, the distribution may comprise a histogram with a fraction of the total volume (of the processed plurality or of the powder) on the y-axis, and the ratio of a maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face (that may be considered an L / D ratio) on the x-axis. By virtue of the melting, as described above, the L / D ratio may be reduced, at least significantly, to lower than 1, preferably to lower than 0.8, further preferably to lower than 0.6. Or, in yet other words, the volumetric relative size distribution may indicate a fraction of the total volume of the processed plurality and / or of the powder occupied by particles with a defined L / D ratio.

[0105] Each of the processed plurality of particles may comprise a particle as described above, and the processed plurality of particles may define a numeric relative size distribution representing a distribution of the total number of particles in the processed plurality and / or in the powder with a ratio of a maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face. In other words, the distribution may comprise a histogram with a fraction of the total number (of the processed plurality or of the powder) on the y-axis, and the ratio of a maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face (that may be considered an L / D ratio) on the x-axis.

[0106] By virtue of the melting, as described above, the L / D ratio may be reduced, at least significantly, to lower than 1, preferably to lower than 0.8, further preferably to lower than 0.6 such that the distribution may have an average, or a median L / D ratio less than 1. Or, in yet other words, the numeric relative size distribution may indicate a fraction of the total number of particles of the processed plurality and / or of the powder made up by particles with a defined L / D ratio.

[0107] Each of the processed plurality of particles may comprise a particle as described above, and the processed plurality of particles may define a numeric relative size distribution representing a distribution of the total number of particles in the processed plurality and / or in the powder with a ratio of a surface area of the substantially curved face to a total surface area of the particle. In other words, the distribution may comprise a histogram with a fraction of the total number (of the processed plurality or of the powder) on the y- axis, and the ratio of the surface area of the substantially curved face to the total surface area of the particle on the x-axis.

[0108] Any of the distributions described above may be characterized, for example, in terms of a width. In particular, the width may be described by a ratio of a difference in the 90thand 10thpercentile x-values relative to the 50thpercentile x-value. For example, when the x- axis comprises the ratio of the surface area of the substantially curved face to the total surface area of the particle, that may be written as CTSR, the width may be defined as (CTSR90 - CTSRio) / CTSRso, where CTSRk denotes the value of the ratio of the surface area of the substantially curved face to the total surface area such that k % of the particles have a ratio of the surface area of the substantially curved face to the total surface area less than CTSRk. In particular, CTSR50 may be considered a median ratio of the distribution.

[0109] In embodiments of the present technology, powders may be produced the distributions of which may be characterized by one of CTSR50 greater than 0.8 and width less than 0.9, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, CTSR50 greater than 0.6 and at most 0.8 and width less than 1.3, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, CTSR50 greater than 0.4 and at most 0.6 and width less than 2, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, CTSR50 greater than 0.2 and at most 0.5 and width less than 2.2, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, and CTSR50 greater than 0.1 and at most 0.2 and width less than 2.5 preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1.

[0110] Similarly, when the x-axis comprises an L / D ratio, the width may be defined as (L / D90 - L / DIO) / L / D5O, with L / Dk defined as the value of L / D such that k % of the particles have a ratio of the maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and the maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face less than L / Dk. In particular, L / D50 may be considered a median ratio of the distribution.

[0111] Alternatively, or additionally, the distributions may be characterized by one of L / D50 greater than 1 and less than 4 and width less than 2, preferably less than 1, further preferably less than 0.5, yet further preferably less than 0.1, L / D50 greater than 0.5 and at most 1 and width less than 3, preferably less than 1, further preferably less than 0.5, yet further preferably less than 0.1, and L / D50 greater than 0.1 and at most 0.5 and width less than 4, preferably less than 1, further preferably less than 0.5, yet further preferably less than 0.1.

[0112] The method may comprise a method as described above, wherein the powder may comprise a powder as described above. According to a fifth aspect, the present invention relates to a use of a powder as described above in an additive manufacturing process.

[0113] The additive manufacturing process may comprise a laser sintering process, such as a selective laser sintering process.

[0114] According to a sixth aspect, the present invention relates to a system for manufacturing a powder for use in an additive manufacturing process, wherein the powder comprises a plurality of particles, wherein the system is configured to produce each of a processed plurality of the plurality of particles from each of a plurality of pre-cursor particles.

[0115] Producing each of the processed plurality of particles may comprise melting, at least in part, each of the plurality of pre-cursor particles.

[0116] The system may be configured to arrange each of the plurality of pre-cursor particles on a substantially flat surface before melting.

[0117] The system may be configured to produce any, preferably each, of the plurality of precursor particles.

[0118] Each of the plurality of pre-cursor particles may comprise a section of a filament.

[0119] The system may be configured to cut the filament.

[0120] The system may comprise a perforated plate comprising at least one channel, each of the at least one channel configured to allow at least one filament through, each of the at least one channel comprising a feed end through which the at least one filament can enter the channel and a cutting end corresponding to an end out of which the at least one filament can exit the channel, wherein the feed end lies in a feed plane of the perforated plate, and the cutting end lies in a cutting plane of the perforated plane. A length of the channel may be in the range defined by 5 and 100 mm, preferably by 15 and 50 mm, further preferably by 20 and 30 mm. A diameter of the channel may be in the range defined by 0.5 and 10 mm, preferably by 1 and 7 mm, further preferably by 1.5 and 5 mm.

[0121] Cutting the filament may comprise guiding the filament through one of the at least one channel.

[0122] The system may be configured to cut a section of the filament extending out of the channel at the cutting end.

[0123] The system may comprise a blade, and the system may be configured to cut the filament with the blade.

[0124] The system may be configured to cut the filament by sliding the blade over the cutting end. The system may be configured to slide the blade over the cutting end periodically with a cutting frequency.

[0125] The system may be configured to guide the filament through the channel at a guiding speed.

[0126] The system may be configured to guide the filament through the channel in a guiding direction.

[0127] An extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction is based, at least in part, on the cutting frequency.

[0128] An extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction is based, at least in part, on the guiding speed.

[0129] The system may be configured to choose the guiding speed based, at least in part, on a desired extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0130] The system may be configured to choose the cutting frequency based, at least in part, on a desired extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0131] Each of the at least one channel may be configured to allow a plurality of filaments through. For any defined channel, the plurality of filaments being pushed through the defined channel may occupy a fraction of the total volume of the defined channel that may be referred to as an occupancy fraction. The occupancy fraction may be in a range defined by 0.1 and 0.6, preferably by 0.2 and 0.5, further preferably by 0.2 and 0.3. The occupancy fraction may, most advantageously, be in the range defined by 0.2 and 0.3 - a higher occupancy fraction may lead to clogging of the channel, whereas a lower occupancy fraction may lead to the filaments not supporting each other enough for a cut to be made or for a cut to be made at a desired extension of the section. The skilled person appreciates that the occupancy fraction may depend, at least in part, on any of the guiding speed, the cutting frequency, a sharpness of the blade, or a force exerted by the blade (that may be based, for example, on a length of the blade).

[0132] The system may be configured to produce a cut plurality of the plurality of pre-cursor particles.

[0133] Producing the cut plurality of the plurality of pre-cursor particles may comprise cutting a plurality of filaments.

[0134] Cutting the plurality of filaments may comprise guiding the plurality of filaments through one of the at least one channel. The at least one channel may comprise a plurality of channels, wherein each of the plurality of channels may be configured to allow a plurality of filaments through.

[0135] Cutting the plurality of filaments may comprise guiding a first guided plurality of the plurality of filaments through a first channel and a second guided plurality of the plurality of filaments through a second channel.

[0136] The system may be configured to twist a bundled plurality of the plurality of filaments together into a filament bundle.

[0137] The system may be configured to twist a first bundled plurality of the plurality of filaments together into a first filament bundle.

[0138] The system may be configured to twist a second bundled plurality of the plurality of filaments together into a second filament bundle.

[0139] The system may be configured to combine the first and the second filament bundles.

[0140] The system may be configured to twist together the bundled plurality of filaments before cutting.

[0141] A diameter of any one of the plurality of filaments may, at least significantly, be identical to a diameter of any other of the plurality of filaments.

[0142] A diameter of a first of the plurality of filaments may be different from a diameter of a second of the plurality of filaments.

[0143] The system may be configured to guide the filament or the plurality of filaments through the channel(s) by means, at least in part, of a fluid flow. In other words, the system may be configured to guide the filament through one of the at least one channel, as described above, by means, at least in part, of a fluid flow. Further, the system may be configured to guide the plurality of filaments through one of the at least one channel, as described above, by means, at least in part, of a fluid flow. Yet further, the system may be configured to guide the first guided plurality of filaments through the first channel and the second guided plurality of filaments through the second channel, as described above, by means, at least in part, of a fluid flow.

[0144] The fluid may comprise any of air, an inert gas, or nitrogen.

[0145] The system may be further configured to reduce a turbulence of the fluid flow.

[0146] The system may be configured to guide the filament or the plurality of filaments through the channel(s) by means, at least in part, of an electrostatic field. In other words, the system may be configured to guide the filament through one of the at least one channel, as described above, by means, at least in part, of an electrostatic field. Further, the system may be configured to guide the plurality of filaments through one of the at least one channel, as described above, by means, at least in part, of an electrostatic field. Yet further, the system may be configured to guide the first guided plurality of filaments through the first channel and the second guided plurality of filaments through the second channel, as described above, by means, at least in part, of an electrostatic field.

[0147] The system may be configured to establish a lower pressure at the cutting end than at the feed end of each of the at least one or plurality of channels. The pressure difference between the feed end and the cutting end may be based, at least in part, on any of the guiding speed of the filament or plurality of filaments, on a level of turbulence of the fluid flow within any of the channels, and on a mass of filaments being guided through the channels. A pressure difference between the feed end and the cutting end may be in the range defined by 0.1 and 1.5 bar, preferably by 0.2 and 1.2 bar, further preferably by 0.3 and 1.0 bar. For example, the feed end may be at atmospheric pressure, i.e., at 1 bar, and the cutting end may be maintained at 0.5 bar.

[0148] The system may be configured to maintain a temperature of the blade below a pre-defined threshold.

[0149] The system may be configured to cool the blade.

[0150] The system may be configured to pump a thermal fluid over a heated element, the heated element in thermal contact with the blade.

[0151] The system may be configured to blow, over the blade, a gas with a temperature, at least significantly, lower than a temperature of the blade.

[0152] The system may be configured to cool the fluid.

[0153] The system may be configured to cool the filament and / or any of the plurality of filaments before cutting.

[0154] The perforated plate may comprise at least one, preferably a plurality of, thermal fluid channel(s) to allow for flow of the thermal fluid.

[0155] At least one, preferably a plurality, further preferably each, of the at least one or plurality of thermal fluid channel(s) may comprise a U-shaped channel, wherein a bend of the U- shaped channel is in thermal contact with the cutting end.

[0156] The gas may be blown in a direction, at least significantly, parallel / anti-parallel to the direction of sliding.

[0157] The perforated plate may comprise at least one, preferably a plurality, of gas channels through which gas is blown over the blade. The blade may be attached to a cutting head.

[0158] The cutting head may be configured to be cooled with a liquid. The attachment of the blade to the cutting head may comprise a thermally conductive attachment, preferably a highly conductive attachment to allow transfer of heat from the blade to the cutting head.

[0159] The filament and / or any of the plurality of filaments may comprise a partially or fully drawn yarn, and wherein the system may be configured to heat the cut section(s) of the filament and / or of any of the plurality of filaments after cutting.

[0160] The system may be configured to heat to a temperature lower than a melting point of the filament and / or of any of the plurality of filaments.

[0161] A result of the heating may be a decrease in an extension of the cut section(s) in at least one direction.

[0162] The system may comprise a furnace.

[0163] The system may be configured to guide each of the plurality of pre-cursor particles through the furnace.

[0164] The system may comprise a conveyor belt configured to pass through the furnace, wherein the conveyor belt may comprise a substantially flat surface.

[0165] The system may be configured to disperse the plurality of pre-cursor particles on the flat surface of the conveyor belt passing through the furnace.

[0166] A temperature of the furnace may be greater than a melting point of any of the plurality of pre-cursor particles.

[0167] At least one of the plurality of pre-cursor particles may comprise a polymer, and the temperature of the furnace may be less than a decomposition temperature of the at least one particle.

[0168] Each of a polymeric plurality of the plurality of pre-cursor particles may comprise a polymer, and wherein the temperature of the furnace is less than a decomposition temperature of any of the polymeric plurality of pre-cursor particles.

[0169] The system may be configured to cool each of the plurality of pre-cursor particles after passing them through the furnace to obtain each of the processed plurality of particles.

[0170] The system may be configured to cool for a duration in the range defined by 0 and Is, preferably by 1 and 5s, further preferably by 5 and 20s, yet further preferably by 20 and 60s, even more preferably greater than 60s. A result of melting, at least in part, each of the plurality of pre-cursor particles may be an increase in a degree of crystallinity of each of the plurality of pre-cursor particles.

[0171] The increase in a degree of crystallinity may be at least 5 % for at least 30 % of the plurality of pre-cursor particles.

[0172] At least one, preferably a plurality, further preferably each, of the processed plurality of particles may comprise a polymer-based particle.

[0173] The polymer may comprise a thermoplastic polymer.

[0174] The system may comprise a sieve.

[0175] The system may be configured to disperse the plurality of pre-cursor particles by means, at least in part, of the sieve.

[0176] The system may be configured to realize a desired areal number density of the plurality of pre-cursor particles on the conveyor belt.

[0177] The desired areal number density may be based, at least in part, on a speed of the conveyor belt.

[0178] The desired areal number density may be based, at least in part, on a size of the sieve.

[0179] The desired areal number density may be based, at least in part, on a throughput of the sieve.

[0180] The plurality of channels may be arranged in one or more circles about a common center.

[0181] The plurality of channels may be arranged eccentrically in the perforated plate.

[0182] At least one, preferably each, of the plurality of channels may, at least substantially, be perpendicular to the cutting plane.

[0183] At least one, preferably a plurality, of the plurality of channels may, at least substantially, not be perpendicular to the cutting plane.

[0184] The system may be configured to rotate the blade with respect to the cutting plane.

[0185] An axis of rotation of the blade may, at least significantly, be perpendicular to the cutting plane.

[0186] The system may be configured to rotate the cutting head. The cutting frequency may be based, at least in part, on a frequency of rotation of the blade.

[0187] A material of the perforated plate, or at least the cutting plane thereof, may be harder than a material of the blade.

[0188] The system may be configured to press the blade against the cutting plane during the cutting.

[0189] A material of the perforated plate, or at least the cutting plane thereof, may be softer than a material of the blade.

[0190] A coefficient of friction between the blade and the cutting plane may be less than 0.5, preferably less than 0.2, further preferably less than 0.3, yet further preferably less than 0.2, even more preferably less than 0.1.

[0191] The blade may be coated with a diamond-like material. The diamond-like material may comprise, for example, any Diamond-like carbon (DLC) material. Further exemplarily, the coating may comprise any of TiN, TiAIN, or AITiSiN.

[0192] The system may comprise a plurality of blades.

[0193] The blade, as described above, may comprise any one of the plurality of blades.

[0194] Each of the plurality of blades may be attached to the cutting head.

[0195] The powder may comprise a powder as described above.

[0196] The system may be configured to perform the method as described above.

[0197] The use may comprise use of a system as described above to perform a method as described above.

[0198] Overall, it may, thus, be understood that embodiments of the present technology relate to a powder comprising at least one, preferably a plurality of, further preferably a majority of, processed particle(s) as described. Each of the at least one processed particle may comprise a particle with a substantially curved face as described above. Preferably, each of the at least one processed particle may further comprise a substantially flat face. The characteristic shape of each of the at least one processed particle may be produced by melting, at least in part, a pre-cursor particle. The pre-cursor particle may be produced by cutting a filament. In order to produce the plurality of processed particles, that may be referred to as the processed plurality of particles, a plurality of pre-cursor particles may be produced, by cutting a plurality of filaments (or by plurally cutting a single filament, as understood by the skilled person), and melted, at least in part. The present invention is also described by the following numbered embodiments.

[0199] Below method embodiments will be discussed. These are abbreviated by the letter "M" followed by a number. Whenever reference is herein made to the "method embodiments", these embodiments are meant.

[0200] Ml. A method for manufacturing a powder for use in an additive manufacturing process, wherein the powder comprises a plurality of particles, and wherein the method comprises producing each of a processed plurality of the plurality of particles from each of a plurality of pre-cursor particles.

[0201] M2. The method according to the preceding embodiment, wherein producing each of the processed plurality of particles comprises melting, at least in part, each of the plurality of pre-cursor particles.

[0202] M3. The method according to the preceding embodiment, wherein the method comprises arranging each of the plurality of pre-cursor particles on a substantially flat surface before melting.

[0203] M4. The method according to any of the preceding method embodiments, wherein the method comprises producing any, preferably each, of the plurality of pre-cursor particles.

[0204] M5. The method according to any of the preceding method embodiments, wherein each of the plurality of pre-cursor particles comprises a section of a filament.

[0205] M6. The method according to the preceding embodiment, wherein the method comprises cutting the filament.

[0206] M7. The method according to the preceding embodiment, wherein cutting the filament comprises guiding the filament through a channel, the channel defined by a feed end, corresponding to an end from which the filament enters the channel, and a cutting end, corresponding to an end out of which the filament exits the channel.

[0207] M8. The method according to the preceding embodiment, wherein the method comprises cutting a section of the filament extending out of the channel at the cutting end.

[0208] M9. The method according to any of the preceding method embodiments and with the features of embodiment M6, wherein the method comprises cutting the filament with a blade.

[0209] MIO. The method according to the preceding embodiment and with the features of the penultimate embodiment, wherein cutting the filament comprises sliding the blade over the cutting end. Mil. The method according to the preceding embodiment, wherein the method comprises sliding the blade over the cutting end periodically with a cutting frequency.

[0210] M12. The method according to any of the preceding method embodiments and with the features of embodiment M7, wherein the method comprises guiding the filament through the channel at a guiding speed.

[0211] M13. The method according to any of the preceding method embodiments and with the features of embodiment M7, wherein the method comprises guiding the filament through the channel in a guiding direction.

[0212] M14. The method according to the preceding embodiment and with the features of embodiment Mil, wherein an extension of the cut section or the pre-cursor particle in a direction at least significantly parallel to the guiding direction is based, at least in part, on the cutting frequency.

[0213] M15. The method according to any of the 2 preceding embodiments and with the features of embodiment M12, wherein an extension of the cut section or the pre-cursor particle in a direction at least significantly parallel to the guiding direction is based, at least in part, on the guiding speed.

[0214] M16. The method according to the preceding embodiment, wherein the method comprises choosing the guiding speed based, at least in part, on a desired extension of the cut section or the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0215] M17. The method according to any of the 3 preceding embodiments, wherein the method comprises choosing the cutting frequency based, at least in part, on a desired extension of the cut section or the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0216] M18. The method according to any of the preceding method embodiments and with the features of embodiment M4, wherein the method comprises producing a cut plurality of the plurality of pre-cursor particles.

[0217] M19. The method according to the preceding embodiment, wherein producing the cut plurality of the plurality of pre-cursor particles comprises cutting a plurality of filaments.

[0218] M20. The method according to the preceding embodiment and with the features of embodiment M7, wherein cutting the plurality of filaments comprises guiding the plurality of filaments through the channel.

[0219] M21. The method according to the penultimate embodiment, wherein cutting the plurality of filaments comprises guiding a first guided plurality of the plurality of filaments through a first channel and a second guided plurality of the plurality of filaments through a second channel, wherein each of the first and the second channels is defined by a feed end, corresponding to an end from which the first and second guided plurality of filaments enters the channel, and a cutting end, corresponding to an end out of which the first and second guided plurality of filaments exits the channel respectively.

[0220] M22. The method according to any of the 3 preceding embodiments, wherein the method comprises twisting a bundled plurality of the plurality of filaments together into a filament bundle.

[0221] M23. The method according to the preceding embodiment, wherein the method comprises twisting a first bundled plurality of the plurality of filaments together into a first filament bundle.

[0222] M24. The method according to the preceding embodiment, wherein the method comprises twisting a second bundled plurality of the plurality of filaments together into a second filament bundle.

[0223] M25. The method according to the preceding embodiment and with the features of the penultimate embodiment, wherein the method comprises combining the first and the second filament bundles.

[0224] M26. The method according to any of the 4 preceding embodiments and with the features of embodiment M19, wherein the method comprises twisting together the bundled plurality of the plurality of the filaments before cutting.

[0225] M27. The method according to any of the preceding method embodiments and with the features of embodiment M19, wherein a diameter of any one of the plurality of filaments is, at least significantly, identical to a diameter of any other of the plurality of filaments.

[0226] M28. The method according to any of the preceding method embodiments and with the features of embodiment M19, but without the features of the preceding embodiment, wherein a diameter of a first of the plurality of filaments is different from a diameter of a second of the plurality of filaments.

[0227] M29. The method according to any of the preceding method embodiments and with the features of any of embodiments M7, M20, and M21, wherein guiding through the channel(s) comprises guiding by means, at least in part, of a fluid flow.

[0228] M30. The method according to the preceding embodiment, wherein the fluid comprises any of air, an inert gas, or nitrogen.

[0229] M31. The method according to any of the 2 preceding embodiments, wherein the method further comprises reducing a turbulence of the fluid flow. M32. The method according to any of the 3 preceding embodiments, wherein guiding through a channel comprises guiding by means, at least in part, of an electrostatic field.

[0230] M33. The method according to any of the preceding method embodiments and with the features of any of embodiments M7, M20, and M21, wherein guiding through the channel(s) comprises establishing a lower pressure at the cutting end than at the feed end.

[0231] M34. The method according to any of the preceding method embodiments and with the features of embodiment M9, wherein the method comprises maintaining a temperature of the blade below a pre-defined threshold.

[0232] M35. The method according to the preceding embodiment, wherein the method comprises cooling the blade.

[0233] M36. The method according to any of the 2 preceding embodiments, wherein the method comprises pumping a thermal fluid over a heated element, the heated element in thermal contact with the blade.

[0234] M37. The method according to any of the 3 preceding embodiments, wherein the method comprises blowing, over the blade, a gas with a temperature, at least significantly, lower than a temperature of the blade.

[0235] M38. The method according to any of the 4 preceding embodiments and with the features of embodiment M29, wherein the method comprises cooling the fluid.

[0236] M39. The method according to any of the 5 preceding embodiments and with the features of any of embodiments M6, and M19, wherein the method comprises cooling the filament and / or any of the plurality of filaments before cutting.

[0237] M40. The method according to any of the preceding method embodiments and with the features of any of embodiments M6, and M19, wherein the filament and / or any of the plurality of filaments comprises a partially or fully drawn yarn, and wherein the method comprises heating the cut section(s) of the filament and / or of any of the plurality of filaments.

[0238] M41. The method according to the preceding embodiment, wherein the method comprises heating to a temperature lower than a melting point of the filament and / or of any of the plurality of filaments.

[0239] M42. The method according to the preceding embodiment, wherein a result of the heating is a decrease in an extension of the cut section(s) in at least one direction.

[0240] M43. The method according to any of the preceding method embodiments and with the features of embodiment M2, wherein melting comprises passing each of the plurality of pre-cursor particles through a furnace. M44. The method according to the preceding embodiment, wherein the method comprises dispersing the plurality of pre-cursor particles on a conveyor belt passing through the furnace.

[0241] M45. The method according to any of the 2 preceding embodiments, wherein a temperature of the furnace is greater than a melting point of any of the plurality of precursor particles.

[0242] M46. The method according to the preceding embodiment, wherein at least one of the plurality of pre-cursor particles comprises a polymer, and wherein the temperature of the furnace is less than a decomposition temperature of the at least one particle.

[0243] M47. The method according to the preceding embodiment, wherein each of a polymeric plurality of the plurality of pre-cursor particles comprises a polymer, and wherein the temperature of the furnace is less than a decomposition temperature of any of the polymeric plurality of pre-cursor particles.

[0244] M48. The method according to any of the 5 preceding embodiments, wherein the method comprises cooling each of the plurality of pre-cursor particles after passing them through the furnace to obtain each of the processed plurality of particles.

[0245] M49. The method according to the preceding embodiment, wherein the method comprises cooling for a duration defined by the range 0 - Is, preferably by 1 - 5s, further preferably by 5 - 20s, yet further preferably by 20 - 60s, even more preferably greater than 60s.

[0246] M50. The method according to any of the preceding method embodiments and with the features of M2, wherein a result of melting, at least in part, each of the plurality of precursor particles is an increase in a degree of crystallinity of each of the plurality of precursor particles.

[0247] M51. The method according to the preceding embodiment, wherein the increase in a degree of crystallinity is at least 5 % for at least 30 % of the plurality of pre-cursor particles.

[0248] M52. The method according to any of the preceding method embodiments, wherein at least one, preferably a plurality, further preferably each, of the processed plurality of particles comprises a polymer.

[0249] M53. The method according to the preceding embodiment, wherein the polymer comprises a thermoplastic polymer. M54. The method according to any of the preceding method embodiments and with the features of embodiment M44, wherein dispersing the plurality of pre-cursor particles comprises sieving the plurality of pre-cursor particles.

[0250] M55. The method according to the preceding embodiment, wherein sieving the plurality of pre-cursor particles comprises realizing a desired areal number density of the plurality of pre-cursor particles on the conveyor belt.

[0251] M56. The method according to the preceding embodiment, wherein the desired areal number density is based, at least in part, on a speed of the conveyor belt.

[0252] M57. The method according to any of the 2 preceding embodiments, wherein the desired areal number density is based, at least in part, on a size of the sieve.

[0253] M58. The method according to any of the 3 preceding embodiments, wherein the desired areal number density is based, at least in part, on a throughput of the sieve.

[0254] Below particle embodiments will be discussed. These are abbreviated by the letter "R" followed by a number. Whenever reference is herein made to the "particle embodiments", these embodiments are meant.

[0255] Rl. A particle, wherein a surface of the particle comprises, at least in part, a substantially curved face.

[0256] R2. The particle according to the preceding embodiment, wherein a ratio of a surface area of the substantially curved face to a total surface area of the particle is less than 1, preferably less than 0.95, further preferably less than 0.9.

[0257] R3. The particle according to any of the preceding particle embodiments, wherein a ratio of a surface area of the substantially curved face to a total surface area of the particle is at least as large as 0.25, preferably at least as large as 0.30, further preferably at least as large as 0.35.

[0258] R4. The particle according to any of the preceding particle embodiments, wherein the substantially curved face, or at least a part thereof, comprises a significantly finite radius of curvature in at least two dimensions.

[0259] R5. The particle according to the preceding embodiment, wherein a defined fraction of the substantially curved face comprises the significantly finite radius of curvature in at least two dimensions, wherein the defined fraction is at least as large as 0.3, preferably at least as large as 0.4, further preferable at least as large as 0.5.

[0260] R6. The particle according to any of the preceding embodiments, wherein the particle comprises a substantially flat face. R7. The particle according to any of the preceding particle embodiments, wherein a maximum extension of the particle in any dimension is 500 pm, preferably 400 pm, further preferably 300 pm, yet further preferably 200 pm, even more preferably 100 pm, even more preferably 50 pm.

[0261] R8. The particle according to any of the preceding particle embodiments and with the features of embodiment R6, wherein a maximum extension of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face is 300 pm, preferably 200 pm, further preferably 100 pm, even more preferably 50 pm.

[0262] R9. The particle according to any of the preceding particle embodiments and with the features of embodiment R6, wherein a maximum extension of the particle in a plane, at least significantly, parallel to the substantially flat face is 500 pm, preferably 400 pm, further preferably 300 pm, yet further preferably 200 pm, even more preferably 100 pm, even more preferably 50 pm.

[0263] R10. The particle according to any of the preceding particle embodiments and with the features of embodiment R6, wherein a ratio of a maximum extension of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particle in a plane, at least significantly, parallel to the substantially flat face is less than 0.7, preferably less than 0.6, further preferably less than 0.5, even more preferably less than 0.4.

[0264] Rll. The particle according to any of the preceding particle embodiments and with the features of embodiments R4, and R6, wherein the substantially curved face defines a boundary of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face.

[0265] R12. The particle according to any of the preceding particle embodiments and with the features of embodiments R4, and R6, wherein the particle comprises, generally, the shape of a frustum of a sphere.

[0266] R13. The particle according to any of the preceding particle embodiments and with the features of embodiments R4, and R6, wherein a cross-section of the particle in a plane, at least substantially, parallel to the substantially flat face is generally elliptical.

[0267] R14. The particle according to the any of the preceding particle embodiments, but without the features of embodiment R4, wherein the particle comprises a generally cylindrical shape.

[0268] R15. The particle according to the preceding embodiment, wherein a ratio of a maximum length and a maximum width of the particle is less than 0.7, preferably less than 0.6, further preferably less than 0.5, even more preferably less than 0.4. R16. The particle according to any of the preceding particle embodiments, wherein the particle comprises a unitary construction.

[0269] R17. The particle according to any of the preceding particle embodiments but without the features of the preceding embodiment, wherein the particle comprises a non-unitary construction.

[0270] R18. The particle according to any of the preceding particle embodiments, wherein the particle comprises a cut artifact.

[0271] R19. The particle according to any of the preceding particle embodiments, wherein a volume of the particle is less than 1.4 x 107pm3, preferably less than 4.2 x 106pm3, further preferably less than 5.2 x 105pm3.

[0272] R20. The particle according to any of the preceding particle embodiments, wherein the particle comprises at least one chemical compound.

[0273] R21. The particle according to the preceding embodiment, wherein the particle comprises a plurality of chemical compounds.

[0274] R22. The particle according to any of the 2 preceding embodiments, wherein at least one of the at least one or plurality of chemical compound(s) comprises one of a polyamide, a polyethylene, a polypropylene, a polyetherketone, a polyoxymethylene acetal, a polytetrafluoroethylene, a polypheneylene sulfide, a polybutylene terephthalate, an aliphatic nylon polyamide, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 10, nylon 10- 10, nylon 10-12, nylon 11, nylon 12, a low-density polyethylene, a medium-density polyethylene, or a high-density polyethylene.

[0275] R23. The particle according to any of the preceding particle embodiments, wherein the particle comprises any of a semi-crystalline or amorphous material-based polymer.

[0276] M59. The method according to any of the preceding method embodiments, wherein each of the processed plurality of particles comprises a particle according to any of the preceding particle embodiments.

[0277] Below powder embodiments will be discussed. These are abbreviated by the letter "P" followed by a number. Whenever reference is herein made to the "powder embodiments", these embodiments are meant.

[0278] Pl. A powder for use in an additive manufacturing process, wherein the powder is manufactured by a method according to any of the preceding method embodiments.

[0279] P2. A powder for use in an additive manufacturing process, wherein the powder comprises a processed plurality of particles, wherein at least one of the processed plurality of particles comprises a particle according to any of the preceding particle embodiments. P3. The powder according to the preceding embodiment, wherein each of the processed plurality of particles comprises a particle according to any of the preceding particle embodiments.

[0280] P4. The powder according to any of the preceding powder embodiments, wherein the processed plurality of particles constitutes a majority of the plurality of particles.

[0281] P5. The powder according to any of the preceding powder embodiments, wherein the processed plurality of particles comprises a majority by weight of the plurality of particles.

[0282] P6. The powder according to any of the preceding powder embodiments, wherein the processed plurality of particles comprises a majority by volume of the plurality of particles.

[0283] P7. The powder according to any of the preceding powder embodiments and with the features of embodiment P3, wherein the processed plurality of particles defines a volume distribution representing a distribution of the total volume of the processed plurality and / or of the powder with a size of the particles.

[0284] P8. The powder according to any of the preceding powder embodiments and with the features of embodiment P3, wherein the processed plurality of particles defines a number distribution representing a distribution of the total number of particles in the processed plurality and / or in the powder with a size of the particles.

[0285] P9. The powder according to any of the preceding powder embodiments and with the features of embodiment P3, wherein each of the processed plurality of particles comprises a particle according to embodiment R6, and wherein the processed plurality of particles defines a volumetric relative size distribution representing a distribution of the total volume of the processed plurality and / or of the powder with a ratio of a maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face.

[0286] PIO. The powder according to any of the preceding powder embodiments and with the features of embodiment P3, wherein each of the processed plurality of particles comprises a particle according to embodiment R6, and wherein the processed plurality of particles defines a numeric relative size distribution representing a distribution of the total number of particles in the processed plurality and / or in the powder with a ratio of a maximum extension of the particles in a direction, at least significantly, parallel to a normal to the substantially flat face and a maximum extension of the particles in a plane, at least significantly, parallel to the substantially flat face.

[0287] Pll. The powder according to the preceding embodiment, wherein a median ratio of the numeric relative size distribution is greater than 1 and less than 4 and wherein a width of the numeric relative size distribution is less than 2, preferably less than 1, further preferably less than 0.5, yet further preferably less than 0.1, or wherein the media is greater than 0.5 and at most 1 and the width is less than 3, preferably less than 1, further preferably less than 0.5, yet further preferably less than 0.1, or wherein the media is greater than 0.1 and at most 0.5 and the width is less than 4, preferably less than 1, further preferably less than 0.5, yet further preferably less than 0.1

[0288] P12. The powder according to any of the preceding powder embodiments and with the features of embodiment P3, wherein each of the processed plurality of particles comprises a particle according to embodiment R6, and wherein the processed plurality of particles defines a numeric surface area distribution representing a distribution of the total number of particles in the processed plurality and / or in the powder with a ratio of an area of the substantially curved face to a total surface area of the particles.

[0289] P13. The powder according to the preceding embodiment, wherein a median ratio of the numeric relative size distribution is greater than 0.8 and a width of the numeric relative size distribution is less than 0.9, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, or wherein the median is greater than 0.6 and at most 0.8 and the width is less than 1.3, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, or wherein the media is greater than 0.4 and at most 0.6 and the width is less than 2, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, or wherein the median is greater than 0.2 and at most 0.5 and the width is less than 2.2, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1, or wherein the median is greater than 0.1 and at most 0.2 and the width is less than 2.5, preferably less than 0.6, further preferably less than 0.3, yet further preferably less than 0.1.

[0290] M60. The method according to any of the preceding method embodiments, wherein the powder comprises a powder according to any of the preceding powder embodiments.

[0291] Below use embodiments will be discussed. These are abbreviated by the letter "U" followed by a number. Whenever reference is herein made to the "use embodiments", these embodiments are meant.

[0292] Ul. Use of a powder according to any of the preceding powder embodiments in an additive manufacturing process.

[0293] U2. Use according to the preceding embodiment, wherein the additive manufacturing process comprises a laser sintering process, such as a selective laser sintering process.

[0294] Below system embodiments will be discussed. These are abbreviated by the letter "S" followed by a number. Whenever reference is herein made to the "system embodiments", these embodiments are meant.

[0295] SI. A system for manufacturing a powder for use in an additive manufacturing process, wherein the powder comprises a plurality of particles, wherein the system is configured to produce each of a processed plurality of the plurality of particles from each of a plurality of pre-cursor particles.

[0296] 52. The system according to the preceding embodiment, wherein producing each of the processed plurality of particles comprises melting, at least in part, each of the plurality of pre-cursor particles.

[0297] 53. The system according to the preceding embodiment, wherein the system is configured to arrange each of the plurality of pre-cursor particles on a substantially flat surface before melting.

[0298] 54. The system according to any of the preceding system embodiments, wherein the system is configured to produce any, preferably each, of the plurality of pre-cursor particles.

[0299] 55. The system according to any of the preceding system embodiments, wherein each of the plurality of pre-cursor particles comprises a section of a filament.

[0300] 56. The system according to the preceding embodiment, wherein the system is configured to cut the filament.

[0301] 57. The system according to any of the preceding system embodiments, wherein the system comprises a perforated plate comprising at least one channel, each of the at least one channel configured to allow at least one filament through, each of the at least one channel comprising a feed end through which the at least one filament can enter the channel and a cutting end corresponding to an end out of which the at least one filament can exit the channel, wherein the feed end lies in a feed plane of the perforated plate, and the cutting end lies in a cutting plane of the perforated plane.

[0302] 58. The system according to the preceding embodiment and with the features of embodiment S6, wherein cutting the filament comprises guiding the filament through one of the at least one channel.

[0303] 59. The system according to the preceding embodiment, wherein the system is configured to cut a section of the filament extending out of the channel at the cutting end.

[0304] S10. The system according to any of the preceding system embodiments and with the features of embodiment S6, wherein the system comprises a blade, and wherein the system is configured to cut the filament with the blade.

[0305] Sil. The system according to the preceding embodiment and with the features of the penultimate embodiment, wherein the system is configured to cut the filament by sliding the blade over the cutting end. 512. The system according to the preceding embodiment, wherein the system is configured to slide the blade over the cutting end periodically with a cutting frequency.

[0306] 513. The system according to any of the preceding system embodiments and with the features of embodiment S8, wherein the system is configured to guide the filament through the channel at a guiding speed.

[0307] 514. The system according to any of the preceding system embodiments and with the features of embodiment S8, wherein the system is configured to guide the filament through the channel in a guiding direction.

[0308] 515. The system according to the preceding embodiment and with the features of embodiment S12, wherein an extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction is based, at least in part, on the cutting frequency.

[0309] 516. The system according to any of the 2 preceding embodiments and with the features of embodiment S13, wherein an extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction is based, at least in part, on the guiding speed.

[0310] 517. The system according to the preceding embodiment, wherein the system is configured to choose the guiding speed based, at least in part, on a desired extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0311] 518. The system according to any of the 3 preceding embodiments, wherein the system is configured to choose the cutting frequency based, at least in part, on a desired extension of the pre-cursor particle in a direction at least significantly parallel to the guiding direction.

[0312] 519. The system according to any of the preceding system embodiments and with the features of embodiment S7, wherein each of the at least one channel is configured to allow a plurality of filaments through.

[0313] 520. The system according to any of the preceding system embodiments and with the features of embodiment S4, wherein the system is configured to produce a cut plurality of the plurality of pre-cursor particles.

[0314] 521. The system according to the preceding embodiment, wherein producing the cut plurality of the plurality of pre-cursor particles comprises cutting a plurality of filaments.

[0315] 522. The system according to the preceding embodiment and with the features of embodiment S19, wherein cutting the plurality of filaments comprises guiding the plurality of filaments through one of the at least one channel.

[0316] S23. The system according to any of the preceding system embodiments and with the features of embodiment S7, wherein the at least one channel comprises a plurality of channels, wherein each of the plurality of channels is configured to allow a plurality of filaments through.

[0317] 524. The system according to the preceding embodiment and with the features of embodiment S21, but without the features of the penultimate embodiment, wherein cutting the plurality of filaments comprises guiding a first guided plurality of the plurality of filaments through a first channel and a second guided plurality of the plurality of filaments through a second channel.

[0318] 525. The system according to any of the 4 preceding embodiments, wherein the system is configured to twist a bundled plurality of the plurality of filaments together into a filament bundle.

[0319] 526. The system according to the preceding embodiment, wherein the system is configured to twist a first bundled plurality of the plurality of filaments together into a first filament bundle.

[0320] 527. The system according to the preceding embodiment, wherein the system is configured to twist a second bundled plurality of the plurality of filaments together into a second filament bundle.

[0321] 528. The system according to the preceding embodiment and with the features of the penultimate embodiment, wherein the system is configured to combine the first and the second filament bundles.

[0322] 529. The system according to any of the 4 preceding embodiments and with the features of any of embodiments S22, and S24, wherein the system is configured to twist together the bundled plurality of filaments before cutting.

[0323] 530. The system according to any of the preceding system embodiments and with the features of embodiment S21, wherein a diameter of any one of the plurality of filaments is, at least significantly, identical to a diameter of any other of the plurality of filaments.

[0324] 531. The system according to any of the preceding system embodiments and with the features of embodiment S21, but without the features of the preceding embodiment, wherein a diameter of a first of the plurality of filaments is different from a diameter of a second of the plurality of filaments.

[0325] 532. The system according to any of the preceding system embodiments and with the features of any of embodiments S7, S22, and S24, wherein the system is configured to guide the filament or the plurality of filaments through the channel(s) by means, at least in part, of a fluid flow.

[0326] 533. The system according to the preceding embodiment, wherein the fluid comprises any of air, an inert gas, or nitrogen. S34. The system according to any of the 2 preceding embodiments, wherein the system is further configured to reduce a turbulence of the fluid flow.

[0327] 535. The system according to any of the 3 preceding embodiments, wherein the system is configured to guide the filament or the plurality of filaments through the channel(s) by means, at least in part, of an electrostatic field.

[0328] 536. The system according to any of the preceding system embodiments and with the features of any of embodiments S7, S22, and S24, wherein the system is configured to establish a lower pressure at the cutting end than at the feed end of each of the at least one or plurality of channels.

[0329] 537. The system according to any of the preceding system embodiments and with the features of embodiment S10, wherein the system is configured to maintain a temperature of the blade below a pre-defined threshold.

[0330] 538. The system according to the preceding embodiment, wherein the system is configured to cool the blade.

[0331] 539. The system according to any of the 2 preceding embodiments, wherein the system is configured to pump a thermal fluid over a heated element, the heated element in thermal contact with the blade.

[0332] 540. The system according to any of the 3 preceding embodiments, wherein the system is configured to blow, over the blade, a gas with a temperature, at least significantly, lower than a temperature of the blade.

[0333] 541. The system according to any of the 4 preceding embodiments and with the features of embodiment S32, wherein the system is configured to cool the fluid.

[0334] 542. The system according to any of the 5 preceding embodiments and with the features of any of embodiments S6, and S21, wherein the system is configured to cool the filament and / or any of the plurality of filaments before cutting.

[0335] 543. The system according to any of the preceding system embodiments and with the features of embodiment S7, and S39, wherein the perforated plate comprises at least one, preferably a plurality of, thermal fluid channel(s) to allow for flow of the thermal fluid.

[0336] 544. The system according to the preceding embodiment, wherein at least one, preferably a plurality, further preferably each, of the at least one or plurality of thermal fluid channel(s) comprises a U-shaped channel, wherein a bend of the U-shaped channel is in thermal contact with the cutting end. 545. The system according to any of the preceding system embodiments and with the features of embodiments Sil, and S40, wherein the gas is blown in a direction, at least significantly, parallel / anti-parallel to the direction of sliding.

[0337] 546. The system according to any of the preceding system embodiments and with the features of embodiments S7, and S40, wherein the perforated plate comprises at least one, preferably a plurality, of gas channels through which gas is blown over the blade.

[0338] 547. The system according to any of the preceding system embodiments and with the features of embodiment S10, wherein the blade is attached to a cutting head.

[0339] 548. The system according to the preceding embodiment and with the features of embodiment S34, wherein the cutting head is configured to be cooled with a liquid.

[0340] 549. The system according to any of the preceding system embodiments and with the features of any of embodiments S6, and S21, wherein the filament and / or any of the plurality of filaments comprises a partially or fully drawn yarn, and wherein the system is configured to heat the cut section(s) of the filament and / or of any of the plurality of filaments after cutting.

[0341] 550. The system according to the preceding embodiment, wherein the system is configured to heat to a temperature lower than a melting point of the filament and / or of any of the plurality of filaments.

[0342] 551. The system according to the preceding embodiment, wherein a result of the heating is a decrease in an extension of the cut section(s) in at least one direction.

[0343] 552. The system according to any of the preceding system embodiments, wherein the system comprises a furnace.

[0344] 553. The system according to the preceding embodiment and with the features of embodiment S2, wherein the system is configured to guide each of the plurality of precursor particles through the furnace.

[0345] 554. The system according to any of the preceding system embodiments and with the features of embodiment S52, wherein the system comprises a conveyor belt configured to pass through the furnace, wherein the conveyor belt comprises a substantially flat surface.

[0346] 555. The system according to the preceding embodiment and with the features of embodiment S53, wherein the system is configured to disperse the plurality of pre-cursor particles on the flat surface of the conveyor belt passing through the furnace.

[0347] S56. The system according to any of the 3 preceding embodiments, wherein a temperature of the furnace is greater than a melting point of any of the plurality of precursor particles. 557. The system according to the preceding embodiment, wherein at least one of the plurality of pre-cursor particles comprises a polymer, and wherein the temperature of the furnace is less than a decomposition temperature of the at least one particle.

[0348] 558. The system according to the preceding embodiment, wherein each of a polymeric plurality of the plurality of pre-cursor particles comprises a polymer, and wherein the temperature of the furnace is less than a decomposition temperature of any of the polymeric plurality of pre-cursor particles.

[0349] 559. The system according to any of the 6 preceding embodiments, wherein the system is configured to cool each of the plurality of pre-cursor particles after passing them through the furnace to obtain each of the processed plurality of particles.

[0350] 560. The system according to the preceding embodiment, wherein the system is configured to cool for a duration in the range defined by 0 and Is, preferably by 1 and 5s, further preferably by 5 and 20s, yet further preferably by 20 and 60s, even more preferably greater than 60s.

[0351] 561. The system according to any of the preceding system embodiments and with the features of S2, wherein a result of melting, at least in part, each of the plurality of precursor particles is an increase in a degree of crystallinity of each of the plurality of precursor particles.

[0352] 562. The system according to the preceding embodiment, wherein the increase in a degree of crystallinity is at least 5 % for at least 30 % of the plurality of pre-cursor particles.

[0353] 563. The system according to any of the preceding system embodiments, wherein at least one, preferably a plurality, further preferably each, of the processed plurality of particles comprises a polymer-based particle.

[0354] 564. The system according to the preceding embodiment, wherein the polymer comprises a thermoplastic polymer.

[0355] 565. The system according to any of the preceding system embodiments, wherein the system comprises a sieve.

[0356] 566. The system according to the preceding embodiment and with the features of embodiment S55, wherein the system is configured to disperse the plurality of pre-cursor particles by means, at least in part, of the sieve.

[0357] S67. The system according to the preceding embodiment, wherein the system is configured to realize a desired areal number density of the plurality of pre-cursor particles on the conveyor belt. 568. The system according to the preceding embodiment, wherein the desired areal number density is based, at least in part, on a speed of the conveyor belt.

[0358] 569. The system according to any of the 2 preceding embodiments, wherein the desired areal number density is based, at least in part, on a size of the sieve.

[0359] 570. The system according to any of the 3 preceding embodiments, wherein the desired areal number density is based, at least in part, on a throughput of the sieve.

[0360] 571. The system according to any of the preceding system embodiments and with the features of embodiment S23, wherein the plurality of channels are arranged in one or more circles about a common center.

[0361] 572. The system according to any of the preceding system embodiments and with the features of embodiment S23, but without the features of the preceding embodiment, wherein the plurality of channels are arranged eccentrically in the perforated plate.

[0362] 573. The system according to any of the preceding system embodiments and with the features of embodiment S23, wherein at least one, preferably each, of the plurality of channels is, at least substantially, perpendicular to the cutting plane.

[0363] 574. The system according to any of the preceding system embodiments and with the features of embodiment S23, but without the features of the preceding embodiment, wherein at least one, preferably a plurality, of the plurality of channels is, at least substantially, not perpendicular to the cutting plane.

[0364] 575. The system according to any of the preceding system embodiments and with the features of embodiments S7, and Sil, wherein the system is configured to rotate the blade with respect to the cutting plane.

[0365] 576. The system according to the preceding embodiment and with the features of embodiment S71, wherein an axis of rotation of the blade is, at least significantly, perpendicular to the cutting plane.

[0366] 577. The system according to any of the 2 preceding embodiments and with the features of embodiment S47, wherein the system is configured to rotate the cutting head.

[0367] 578. The system according to any of the 3 preceding embodiments and with the features of embodiment S12, wherein the cutting frequency is based, at least in part, on a frequency of rotation of the blade.

[0368] S79. The system according to any of the preceding system embodiments and with the features of embodiments S7, and S10, wherein a material of the perforated plate, or at least the cutting plane thereof, is harder than a material of the blade. S80. The system according to the preceding embodiment and with the features of embodiment Sil, wherein the system is configured to press the blade against the cutting plane during the cutting.

[0369] 581. The system according to any of the preceding system embodiments and with the features of embodiments S7, and S10, but without the features of any of the 2 preceding embodiments, wherein a material of the perforated plate, or at least the cutting plane thereof, is softer than a material of the blade.

[0370] 582. The system according to the preceding embodiment and with the features of embodiment Sil, wherein a coefficient of friction between the blade and the cutting plane is less than 0.5, preferably less than 0.4, further preferably less than 0.3, yet further preferably less than 0.2, even more preferably less than 0.1.

[0371] 583. The system according to any of the 2 preceding embodiments, wherein the blade is coated with a diamond-like material.

[0372] 584. The system according to any of the preceding system embodiments, wherein the system comprises a plurality of blades.

[0373] 585. The system according to the preceding embodiment and with the features of embodiment S10, wherein the blade comprises any one of the plurality of blades.

[0374] 586. The system according to any of the 2 preceding embodiments and with the features of embodiment S47, wherein each of the plurality of blades is attached to the cutting head.

[0375] 587. The system according to any of the preceding system embodiments, wherein the powder comprises a powder according to any of the preceding powder embodiments.

[0376] 588. The system according to any of the preceding system embodiments, wherein the system is configured to perform the method according to any of the preceding method embodiments.

[0377] U3. Use according to any of the preceding use embodiments, wherein the use comprises use of a system according to any of the preceding system embodiments to perform a method according to any of the preceding method embodiments.

[0378] Brief Figure

[0379] Figure 1 depicts an embodiment of a method according to the present invention;

[0380] Figure 2 depicts a microscopic image of a processed plurality of particles;

[0381] Figure 3 depicts feeding and cutting of filaments according to an embodiment of the present invention; Figure 4a depicts a cross-sectional view of a perforated plate according to the present invention;

[0382] Figure 4b depicts a side-view of filaments fed into a perforated plate according to the present invention; and

[0383] Figure 5 depicts melting of pre-cursor particles according to the present invention.

[0384] Detailed Figure Description

[0385] Figure 1 depicts an embodiment of a method for producing a powder according to the present invention. The powder may, in particular, be suitable for use in an additive manufacturing process, such as a laser sintering process. However, the powder may be suitable also for use in other processes such as in rotational molding, coating, or as an ingredient for paints and coatings.

[0386] The powder may comprise a plurality of particles. A processed plurality of the plurality of particles may each be produced from each of a plurality of pre-cursor particles. In other words, one pre-cursor particle may result in one processed particle. The processed plurality of particles may include at least some of the plurality of particles. Preferably, the processed plurality of particles may include a majority, i.e., at least 50%, of the plurality of particles. In other words, the processed plurality may comprise at least 50% of the plurality of particles. Alternatively, the processed plurality may comprise at least 60%, more preferably at least 65% of the plurality of particles.

[0387] Each of the plurality of pre-cursor particles may comprise a section (i.e., a cut portion) of a filament. Embodiments of the present invention relate to production of the processed plurality of particles and may comprise production of a cut plurality of the plurality of precursor particles. The cut plurality of pre-cursor particles may include any, preferably each, of the plurality of pre-cursor particles.

[0388] However, it may be understood that embodiments of the present invention may relate only to producing the processed plurality of particles from pre-cursor particles but not to the production of the pre-cursor particles, or only to production of some of the plurality of precursor particles. In other words, in some embodiments, at least some of the steps of the method, as depicted in Figure 1, may be omitted.

[0389] Each of the plurality of pre-cursor particles may comprise a polymer. For example, the polymer may comprise any of a polyamide, a polyethylene, a polypropylene, a polyetherketone, a polyoxymethylene acetal, a polytetrafluoroethylene, a polypheneylene sulfide, a polybutylene terephthalate, an aliphatic nylon polyamide, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 10, nylon 10-10, nylon 10-12, nylon 11, nylon 12, a low- density polyethylene, a medium-density polyethylene, or a high-density polyethylene. As a result, each of the processed plurality of particles may comprise a polymer, the polymer being, at least substantially, identical to the polymer comprised by the corresponding precursor particle. Producing the cut plurality of pre-cursor particles may comprise cutting one or more filaments. Any, preferably each, of the one or more filaments may comprise a polymer. For example, the polymer may comprise any of a polyamide, a polyethylene, a polypropylene, a polyetherketone, a polyoxymethylene acetal, a polytetrafluoroethylene, a polypheneylene sulfide, a polybutylene terephthalate, an aliphatic nylon polyamide, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 10, nylon 10-10, nylon 10-12, nylon 11, nylon 12, a low-density polyethylene, a medium-density polyethylene, or a high-density polyethylene. As a result, each of the cut plurality of pre-cursor particles, as well as each of the processed plurality of particles may comprise a polymer, as described above.

[0390] In a first step, Al, a filament may be fed into a channel. The channel may comprise a substantially linear channel. Alternatively, or additionally, a plurality of filaments may be fed into the channel. Yet further alternatively, or additionally, and preferably, a first plurality of filaments, that may be referred to as a first guided plurality, may be fed into a first channel, and a second plurality of filaments, that may be referred to as a second guided plurality, may be fed into a second channel. In other words, a plurality of channels may be available, each of the plurality of channels configured to allow a plurality of filaments through and a plurality of filaments may be fed through each of at least some of the plurality of channels. Each of the plurality of channels may comprise a substantially linear channel.

[0391] Feeding a single filament may be of advantage in allowing better control in guiding the filament through the channel. However, the number of cut sections produced may be reduced, decreasing an overall throughput of the process. Feeding a large number of filaments may allow for increase in throughput but may be difficult to guide through the channel. It may be of advantage to feed a plurality of filaments through any one of the plurality of channels such that a fraction of the volume of the channel occupied by the plurality of filaments is at most 60%, preferably at most 50%, further preferably at most 30%. A fraction below 30% may be of particular advantage in achieving optimum cutting results, as described further below.

[0392] The plurality of channels may be comprised in a perforated plate, for example. An end of the channel into which the one or more filaments may be inserted into the channel may be referred to as a feed end of the channel. The feed ends of each of the plurality of channels may lie in a plane of the perforated plate, that may be referred to as a feed plane of the perforated plate.

[0393] The one or more filaments may exit the corresponding channel at another end of the channel, that may be referred to as a cutting end of the channel. In other words, each of the one or more filaments may enter a channel at the feed end of the channel, and exit the channel at the cutting end of the channel. The cutting ends of each of the plurality of channels may lie in a plane of the perforated plate, that may be referred to as a cutting plane of the perforated plate. Generally, the plurality of channels may comprise holes bored through the perforated plate that may extend from one face of the perforated plate to an opposite face of the perforated plate.

[0394] The plurality of channels may or may not be parallel to each other. Further, the plurality of channels may or may not be arranged such that the feed end and the cutting end of any channel are directly opposite each other. The plurality of channels may be arranged in one or more circles around a common center. In other words, the feed ends and / or the cutting ends of the plurality of channels may be arranged in one or more circles around a common center. Note that the common center of the feed ends may not be coaxial with the common center of the cutting ends. Alternatively, the plurality of channels may be arranged eccentrically.

[0395] Any of the plurality of filaments guided through one channel may be bundled together to form a bundled plurality of filaments. In other words, any one channel may hold one or more bundles of filaments and any number (including zero) of unbundled filaments. Bundling may be of advantage in improving an ability to guide the bundled plurality of filaments through the channel. Bundling together may comprise any of placing, collecting, or combining the plurality of filaments into a single group or cluster.

[0396] Bundling together may further comprise twisting together the plurality of filaments. A plurality of bundled pluralities of filaments may be further twisted together before feeding them into a channel.

[0397] The plurality of filaments fed into one channel may comprise filaments of, at least significantly, identical diameters. Alternatively, the plurality of filaments fed into one channel may comprise filaments of different diameters. Feeding filaments of, at least significantly, identical diameters may result in the plurality of pre-cursor particles having a narrow size distribution.

[0398] The plurality of filaments fed into one channel may comprise filaments of, at least significantly, identical compositions. Alternatively, the plurality of filaments fed into one channel may comprise filaments of different compositions. For example, half of the plurality of filaments may comprise one composition, while the other half may comprise another composition. As may be appreciated, any suitable combination of different compositions may be used.

[0399] In a next step, A2, the one or more filaments may be cut by means, at least in part, of a blade. The blade may, for example, slide over the cutting end, thus cutting the section of the one or more filaments extending beyond the cutting end. In embodiments of the present invention, a plurality of blades may be employed for cutting. In the following, reference will be made to cutting of the one or more filaments by means, at least in part, of a blade. The blade may be understood to, then, comprise any one of the plurality of blades. The method may comprise cutting the one or more filaments periodically at a cutting frequency. In other words, the blade may be slid over the cutting end periodically with the cutting frequency. For example, each of the plurality of blades may be attached to a cutting head, that may be configured to rotate about an axis, at least significantly, perpendicular to the cutting plane of the perforated plate. The cutting frequency may be based, at least in part, on a frequency of rotation of the cutting head. In particular, the cutting frequency may be proportional to the frequency of rotation. As may be appreciated, the cutting frequency may, at least significantly, be identical to the frequency of rotation in so far as the cutting frequency relates to cutting of the one or more filaments by a defined blade.

[0400] The one or more filaments may be guided through any of the channels by means, at least in part, of an electrostatic field. Alternatively, or additionally, a fluid flow may be used, at least in part, for guiding. The fluid may comprise any of air, nitrogen, or an inert gas. The fluid flow may be established by means of a pressure difference. In particular, a pressure at the feed end may be greater than a pressure at the cutting end of a channel, such that the one or more filaments are "sucked" towards the cutting end. The creation of a relative negative pressure at the cutting end may be of advantage in reducing a turbulence in the fluid allowing for better reproducibility and higher efficiency in the volume of fluid needed for the process.

[0401] The one or more filaments may be guided through any of the channels at a guiding speed. As may be appreciated by the skilled person, the guiding speed may depend, at least in part, on the pressure difference between the two ends of the channel, on dimensions of the channel, on the fraction of the volume of the channel occupied by the one or more filaments, and on a speed at which the one or more filaments may be fed into the channel. The feed rate into the channel may be controlled, for example, by controlling a rotational speed of a spool over which the one or more filaments may be bound.

[0402] An extension of the section in a direction, at least significantly, perpendicular to the cutting direction, that may be considered a length of the section, may be based, at least in part, on any of the cutting frequency or the guiding speed. In some embodiments, the cutting frequency and / or the guiding speed may be chosen to produce sections of a pre-defined length.

[0403] In some embodiments, the one or more filaments may comprise a partially or fully drawn yarn. A partially or fully drawn yarn may be stiffer than an undrawn yarn and may, thus, be easier to cut. The drawing of the yarn may be, at least partially, reversed by heating the filament, or the sections thereof. The heating of the sections may, thus, allow producing sections of different extensions. Thus, in some embodiments, the method may comprise an auxiliary step, A2', comprising heating the cut sections to a temperature below the melting point of the filament(s), or of the section(s) thereof. For example, a filament may be stretched to three times its length, and sections of length 100 pm may be cut from it. By heating the cut sections, the length may be reduced to ~ 30 pm. As may be appreciated, the decrease in length may be accompanied by an increase in at least one of the other dimensions as the total mass of the section is conserved. The plurality of cut sections obtained at the end of steps A2 / A2' may correspond to the cut plurality of pre-cursor particles described above. As may be appreciated by the skilled person, the cut sections may comprise a generally cylindrical shape, as described above. A cross-section of the generally cylindrical shape perpendicular to a length of the cylinder (i.e., along the length of the section, length being described as above) may, however, not necessarily correspond to a circle. If the cut section is cut from a filament, the cross-section may be substantially circular. However, sections may alternatively, or additionally, be cut from a film, in which case the cross-section may depart from substantial circularity.

[0404] A third step, A3, may comprise arranging the plurality of pre-cursor particles, corresponding to the sections of the one or more filaments as described above, possibly after heating as described above, on a conveyor belt. The conveyor belt may comprise a substantially flat surface over which the plurality of pre-cursor particles may be arranged.

[0405] The step A3 may further comprise realizing a desired areal number density of the precursor particles on the conveyor belt. In particular, the desired areal number density may be chosen such that agglomeration of the pre-cursor particles, or at least of a fraction thereof, is reduced. For example, it may be of advantage to reduce agglomeration of large (for example, greater than ~ 30 pm) pre-cursor particles.

[0406] The arrangement on the conveyor belt may, advantageously, be carried out by means, at least in part, of a sieve, such as a vibrating sieve. In particular, pre-cursor particles that are smaller than a size of a mesh of the sieve may cluster on the conveyor belt. However, during a subsequent melting phase, as described below, they may melt together to form a larger particle or may decompose due to the high temperature. As may be appreciated by the skilled person, particles of size less than ~ 10 pm may not be suitable for use in additive manufacturing processes. By reducing, due to agglomeration, a number of small particles, as described above, embodiments of the present technology may, thus, also improve a utility of the resulting powder for additive manufacturing processes.

[0407] In a fourth step, A4, the plurality of pre-cursor particles may be conveyed through a furnace. A temperature of the furnace may be greater than a melting point of any of the plurality of pre-cursor particles. The temperature of the furnace may, further, be lower than a decomposition temperature of any of the plurality of pre-cursor particles that may each comprise a polymer, as described above.

[0408] A result of conveying the plurality of pre-cursor particles through the furnace may be a melting, at least in part, of at least one, preferably each, of the plurality of pre-cursor particles. As each of the plurality of pre-cursor particles is arranged on the flat surface of the conveyor belt, at least some, preferably a majority, of the plurality of, at least partially, melted pre-cursor particles may comprise a substantially flat face. The melting, at least in part, of the plurality of pre-cursor particles may further result in a change in a degree of crystallinity of at least some, preferably each, of the plurality of precursor particles.

[0409] In a fifth step, A5, the plurality of, at least partially, melted pre-cursor particles may be cooled to obtain each of the processed plurality of particles.

[0410] In some of the pre-cursor particles, the melting, at least in part, of the pre-cursor particles may lead to formation of generally cylindrical particles that are substantially collapsed along the length. Thus, the processed plurality of particles may comprise particles that are generally cylindrical but have a ratio of a maximum length to a maximum width less than 1, preferably less than 0.8, further preferably less than 0.6, even more preferably less than 0.5.

[0411] Alternatively, melting, at least in part, of the pre-cursor particles, as described above, may produce a curved face overlaid over a substantially flat face in at least some of the processed plurality of particles. The curved face may comprise a finite, non-zero radius of curvature in at least two, preferably exactly two, dimensions. In other words, the radius of curvature may be significantly different from both zero and infinity in at least two dimensions. The non-zero radii of curvature in the at least two dimensions may or may not be, at least significantly, identical. The at least some of the processed plurality of particles, so produced, may further be characterized as comprising a shape generally as that of a frustum of a sphere.

[0412] The above shapes of at least some of the processed plurality of particles may lend surprising characteristics to the powder comprising the processed plurality of particles. In particular, the powder may exhibit relatively high bulk density, a good Hausner factor value, such as a Hausner factor less than 1.3, preferably less than 1.2, further preferably less than 1.1, and favorable layer application behavior, for example, in a laser sintering process. Favorable layer application behavior may be understood to comprise reduction in agglomeration of particles in the powder during the process of applying a layer (for additive manufacturing) or in a number of visible grooves.

[0413] Thus, embodiments of the present technology allow manufacturing a powder for use in an additive manufacturing process, the powder comprising a plurality of particles, of which a processed plurality may comprise particles produced as described above.

[0414] In the process of cutting the one or more filaments, as described above, the blade may get heated. The heated blade may result in melting of the filament, at least partly, during cutting. As a result, the cut made by the blade may not be ideal. The method according to the present invention may further comprise maintaining a temperature of the blade below a pre-defined threshold / temperature. The pre-defined temperature may be chosen so as to minimize melting, at least in part, of the filament during cutting. The maintenance of the temperature of the blade below the pre-defined threshold may be achieved by several means. For example, the perforated plate may comprise a thermally conductive material and may comprise one or more thermal channels through which a thermal fluid may be driven. The thermal channel(s) may be arranged so that the thermal fluid comes in thermal contact with the cutting plane of the perforated plate. For example, the thermal channel(s) may comprise U-shaped channel(s) with the bend of the U being arranged, at least significantly, directly underneath the cutting plane.

[0415] The thermal fluid may comprise any fluid that may absorb heat, at least indirectly, from the blade. For example, via the thermal channel, it may be driven between a heat sink and the cutting plane. The thermal fluid may absorb heat from the cutting plane and release it into the heat sink, thereby cooling down.

[0416] Alternatively, or additionally, the cutting head to which the blade is attached may be provided with a cooling mechanism similar, for example, to the mechanism described above. Alternatively, or additionally, the one or more filaments may be cooled before being fed through the one or more channels. Alternatively, or additionally, the fluid used to guide the one or more filaments through the one or more channels may be cooled. Alternatively, or additionally, a cold gas may be blown over the blade in a direction, at least significantly, parallel / anti-parallel to the cutting direction. Alternatively, or additionally, a cold gas may be blown over the blade via one or more gas channels in the perforated plate.

[0417] Another relevant aspect of the process as described above may be a decrease over time in a sharpness of the blade. To maintain, at least as much as possible, the sharpness of the blade, the method may further comprise choosing a material of the blade and of the perforated plate appropriately.

[0418] For example, the material of the perforated plate may be chosen to be harder than the material of the blade, and the blade may be slid over the cutting end such that contact with a defined pressure is established between at least an edge of the blade and the perforated plate. The contact may, thus, sharpen at least the edge of the blade during the cutting.

[0419] Alternatively, if a softer material is chosen for the perforated plate, the material may be chosen such that a coefficient of friction between at least an edge of the blade and the perforated plate is low. Thus, wearing as well as heating of the blade may be, advantageously, reduced. For example, the blade may be coated with a coating comprising a Diamond-like carbon (DLC) material, TiN, TiAIN, or AITiSiN.

[0420] Figure 2 depicts an image of a plurality of particles produced using the method as described above. As depicted in Figure 2, the plurality of particles, that may be comprised in the processed plurality of particles described above, for example, comprise a substantially flat face, and a curved face, wherein the curved face defines a boundary of the corresponding particle in a direction, at least significantly, parallel to a normal to the substantially flat face. Figure 2 also depicts some particles comprising needle-like structures instead of a substantially flat face. These structures may be considered an artifact of the cutting process, wherein the cut section of the filament may be dragged along with the blade while cutting until it eventually breaks away from the filament, or wherein a part of the filament slips between the blade and the cutting plane during cutting. It may be advantageous that such particles do not make up more than 10%, preferably not more than 7%, further preferably not more than 5%, yet further preferably not more than 1% of the total volume and / or weight and / or number of the plurality of particles in the powder.

[0421] Reference will now be made to Figures 3 to 5 that depict different components of an embodiment of a system according to the present invention. The system depicted in Figures 3 to 5 may be used to manufacture the powder comprising the processed plurality of particles as described above.

[0422] Figure 3 depicts a creel comprising a plurality of spools 102. A filament 104 may be wrapped around each spool 102. Each spool 102 may be configured to rotate about an axis such that the filament 104 wrapped around the spool 102 may be unwound. A speed of rotation of the spool 102 may be controlled, for example, to control a speed at which the filament 104 is unwound, and thus to control a speed at which the filament 104 is fed into a perforated plate 106. The filaments 104 from a plurality of spools 102 may be bundled, twisted, and / or multiplexed together, as described further below, into a bundled plurality of filaments 104' before guiding the bundled plurality to the perforated plate 106.

[0423] The perforated plate 106 may comprise a plurality of channels 116 (as depicted more clearly in Figures 4a and 4b) through which a subset of the set of the plurality of filaments 104' is guided. In other words, at least some of the plurality of filaments 104' may be guided through one of the plurality of channels 116 and at least some other of the plurality of filaments 104' may be guided through another of the plurality of channels 116.

[0424] The channels 116 are depicted in Figures 4a and 4b as being linear and, at least substantially, straight such that an end through which a filament 104 (or a plurality thereof) is fed into the channel 116, that may be referred to as a feed end, is directly horizontally opposite an end through which the filament 104 exits the channel, that may be referred to as a cutting end of the channel. However, in some embodiments of the present invention, the channel may not be horizontally straight such that the feed and the cutting ends are not, at least significantly, directly opposite each other.

[0425] Further, the channels 116 are depicted as comprising a concentric arrangement - such arrangement may require alignment, thus making fabrication of the perforated plate 106 complex. Alternatively, the channels 116 may be fabricated eccentric, allowing simpler fabrication of the perforated plate 106.

[0426] Figure 3 further depicts a cutting chamber 112 in which the filament 104 is cut. In particular, a section of the filament 104 extending out of the cutting end of a channel 116 may be cut. The cutting ends of all the channels 116 may be comprised in a plane of the perforated plate 106, that may be referred to as a cutting plane. One or more blades 114, attached to a cutting head 110, may be slid over the cutting plane, effecting cuts of the plurality of filaments 104' guided through the plurality of channels 116. In particular, the one or more blades 114 may be rotated along an axis such that sections of the filament(s) 104 may be cut, at least significantly, perpendicular to a length of the filament(s) 104.

[0427] The cutting head 110 may be pushed against the cutting plane of the perforated plate 106 with a defined force so as to improve an efficiency of the cutting process. The defined force may be in the range defined by 0.1 and 500, preferably by 0.15 and 400, further preferably by 350, yet further preferably by 1 and 50 N / blade, for example. In other words, the defined force may depend on the number of blades attached to the cutting head 110 and may lie in the ranges defined above adjusted suitably for the number of blades attached to the cutting head 110.

[0428] A low-pressure region may be established in the cutting chamber 112 by means of a vacuum pump 108. For example, a pressure difference between the cutting chamber and an external environment around the cutting chamber may be in the range defined by 0.1 and 1 bar. As a consequence of the low pressure, filaments 104 may be "sucked" into the channels 116 towards the cutting plane with the help, for example, of air. As described above, other suitable fluids may be alternatively, or additionally, used. Establishing the low-pressure region within the cutting chamber 112 may be of advantage in reducing a turbulence of the air, allowing better reproducibility of the process.

[0429] With reference to Figure 5, the cut sections of the filament(s) 104, 104', corresponding to pre-cursor particles, as described above, may be sieved by means, for example, of a sieve 202 to achieve a defined and / or desired areal number density on a conveyor belt 210. As described above, the defined and / or desired areal number density may be chosen to avoid formation of agglomeration of the cut sections.

[0430] The conveyor belt 210 may be configured to carry the cut sections through a furnace 204. The furnace 204 may comprise, for example, heating elements 206, to heat the cut sections. A temperature of the furnace 204 may be higher than a melting point of the cut sections, such that the cut sections melt, at least in part, on passing through the furnace 204. Because the cut sections lie on a flat surface, that of the conveyor belt 210, the particles exiting the furnace have a characteristic flattened surface. The particles exiting the furnace may constitute the processed plurality of particles, as described above, and may be extracted by means of an extraction element 208.

[0431] In some embodiments, the cut sections of the filament(s) 104, 104' may be further processed before being sieved onto the conveyor belt 210. Further processing may, in particular, comprise heating the cut sections to a temperature lower than a melting point of the cut sections to produce the pre-cursor particles described above. This may, in particular, be of advantage when the filament 104 comprises a partially or fully drawn yarn (PDY / FDY). Heating the cut sections may cause them to shrink such that pre-cursor particles of a smaller length may be produced.

[0432] To summarize, embodiments of the present technology relate to a method and a system for manufacturing a powder and may comprise any of the following aspects. Note that the following aspects are to be considered exemplary, but not limiting, aspects of the present invention.

[0433] Single or multiple filaments 104, 104' may be cut by feeding them through a channel 116 to a cutting plane in which one or more rotating blades 114 may circulate. The cutting process may be carried out in a cutting chamber 112, i.e., the channel 116 may open into the cutting chamber 112. This may be of advantage in allowing creation of a low-pressure region in the cutting chamber 112, as described above.

[0434] While a single filament 104 may also be used, preferably a plurality of filaments 104' may be used. A number of channels 116 through which the filament(s) 104, 104' may be fed may be at least 1. Typical dimensions of the filament 104 may, for example, comprise a diameter of 20 pm, 25 pm, 30 pm, or 40 pm. Even higher diameters may be used.

[0435] A bundle of filaments 104' may be fed into each channel 116. A number of filaments 104 in a bundle 104' may be at least 1. Channels 116 may preferably be filled with filaments 104' up to 30% of the available channel volume in order to achieve an optimum cutting result. The plurality of filaments 104' can be twisted and multiplexed in different ways ("multiplexing" meaning combining pluralities of filaments 104', e.g., 3 pluralities of filaments 104' of 30 filaments 104 each bundled into a plurality of 90 filaments 104').

[0436] The plurality of filaments 104' can comprise filaments 104 with identical or different diameters. The plurality of filaments 104' can also comprise several materials, e.g., bicomponent or tricomponent yarn. The plurality of filaments 104' may be guided in the channel 116 with the help of an air, generally fluid, flow. The air may be guided in such a way that a minimum of turbulence occurs. Further, a ratio of a number of filaments 104 in a channel 116 to a diameter of the channel 116 may be selected in such a way that the filaments 104, 104' may be sufficiently supported by the channel 116 without getting caught in the channel 116. The air flow may be generated by negative pressure in the cutting chamber 112. The air flow may be generated by overpressure on the feed end of the channel 116 by, e.g., a Venturi nozzle. The plurality of filaments 104' may be, additionally, or alternatively, be guided in the channel 116 with the help of an electrostatic field.

[0437] The feed of the filaments 104 may be controlled in order to control the length of the resulting cut sections or pre-cursor particles. Assuming that the plurality of filaments 104 is unwound from spools 102 as a semi-finished product, multiple options for feed control may exist: Feed control may be achieved through driven bobbins: The spools 102 may be driven in a controlled manner and thus unwind the plurality of filaments 104 at a predetermined speed. The air flow in the channel 116 may be set so that the unwound plurality 104' may be sufficiently tensioned and may be continuously fed to the cutting end.

[0438] Feed control by godets: The spools 102 may not be driven and the plurality of filaments 104 may be unwound. The feed rate may be controlled by guiding the plurality of filaments 104 over pairs of godets (or other suitable combinations of rotating rollers), as is also known from spinning technology.

[0439] Feed control by a pair of rollers: The plurality of filaments 104 may be conveyed by a pair of rollers, whereby the rotation axes of the rollers are parallel to each other and a gusset area may be formed between them. The gusset area may be so narrow that the plurality of filaments 104 fits through it and a conveying effect (i.e., a pushing of the filaments) may be effected. The rollers can be coated to enhance the conveying effect (e.g. with rubber). Similarly, a pair of conveyor belts (e.g., double belt conveyor, double belt press) may also be used.

[0440] The plurality of filaments 104 may also come directly from the spinning process. Galettes (special pairs of rollers used in textile processing) may be typically used to control the feed rate.

[0441] The blades 114 may be attached to a (preferably rotationally symmetrical) cutting head 110, which may be driven in rotation. Alternative cutting methods may include translational oscillating blades (as with beard trimmers). However, the rotating blades may be particularly advantageous.

[0442] The size of the cut sections or pre-cursor particles produced may depend, at least in part, on the filament feed rate, cutting frequency (speed of the cutting head 110 x number of blades 114), and the diameter of the filaments 104. Fluctuations in these parameters or in the reliability of the cutting processes (e.g. decreasing sharpness of the blades 114) may lead to fluctuations in the size of the cut sections or pre-cursor particles produced.

[0443] By using different filament diameters, multimodal particle size distributions can be produced in a targeted manner. The particle size distribution of the powder can also be influenced by subsequent sieving or sifting processes.

[0444] The size of the particles may be determined, at least in part, by the feed rate of the plurality of filaments 104 and the rotational speed of the cutting head 110 and the number of blades 114.

[0445] The channels 116 for guiding the plurality of filaments 104, 104' can be arranged in one or more circles on the cutting plane. The center of the circles and the axis of rotation of the cutting head 110 may aligned (concentric arrangement); the channels 116 may be contained in a so-called perforated plate 106. However, for such arrangement, alignment may be required. Alignment may be avoided in an eccentric arrangement that can also be used to force the pulling cut more strongly.

[0446] Channels 116 may be arranged perpendicular or non-perpendicular to the cutting plane. The blades 114 may effect a pulling cut.

[0447] The blades 114 may be self-sharpening. The rotating blades 114 may rest on the perforated plate 106 and shave off the filaments 104, 104' fed out of it. The area of the perforated plate 106 on which the blades 114 rest may also be referred to as a running surface. The blades 114 can be pressed against the perforated plate 106 with a defined force (contact pressure) during the cutting process. The blades 114 may be made of a softer material than the perforated plate 106, so that the blades 114 may be constantly worn and constantly sharpened on the perforated plate 106.

[0448] Alternatively, the blades 114 may not be self-sharpening. The blades 114 may be made of a harder material than the perforated plate 106 (the perforated plate 106 made of steel or ceramic) so that the blades 114 hardly wear out, but are also no longer self-sharpening. It may be then be advantageous for the running surface to be made of a material with particularly good sliding properties. This can also minimize blade wear and reduce the heat generated by friction between the blades 114 and the running surface. Blades 114 may be additionally coated (e.g., with diamond-like materials) to increase the service life, i.e. the blades may retain their sharpness for longer.

[0449] Cooling the blades 114 and the perforated plate 106 may be advantageous to prevent the cut sections from melting on the blades 114. Several methods may be used for cooling.

[0450] The perforated plate 106 may be provided with internal cooling. For example, water (or another medium) may be pumped through cooling channels that may be arranged as directly as possible under / next to the cutting plane. The temperature of the water may be controlled by a temperature control unit. Alternatively, or additionally, a heat pipe (pipe in which a medium may be vaporized, condensed at another location, and then fed back to the area to be cooled) may be arranged as directly as possible below / level with the cutting plane. Alternatively, or additionally, additional holes or channels through which cooling air may be blown onto the blades 114 may be provided. The arrangement of the additional holes or channels may similar to the filament channels 116 or may be different, e.g., outside the cutting plane, tangential to blade rotation circle inside or outside.

[0451] Further, blades 114 may be made slim in the cutting area and more voluminous behind it (reduced contact surface may reduce heat of friction, increased surface area behind may increase heat transfer / cooling capacity).

[0452] The cutting head 110 may additionally be equipped with liquid cooling. Additionally, or alternatively, the cutting head 110 may be made from special extremely conductive alloys. Additionally, or alternatively, a length of the blade 114 may be reduced. Any of the plurality of filaments 104' may be additionally cooled before being fed into the channel 116, or before exiting at the cutting end. The fluid used to guide the filament(s) 104, 104' in the channels 116 may be cooled before it is fed in.

[0453] Any of the plurality of filaments 104' can be undrawn, partially drawn (PDY - partially drawn yarn) or fully drawn (FDY - fully drawn yarn). This may result in the following properties for the pulverization process according to the invention.

[0454] PDY / FDY may result in a stiffer filament 104: The stiffer the filament 104, the lower the chance that it will evade the cut - i.e., yield may be increased.

[0455] Depending on the plastic, stretching can be partially or completely reversed by heating the material (below the melting temperature range). For example, a filament 104 may be stretched by a factor of 3. Cut sections with a length of 100 pm may be produced. The stretching may be reversed by heat treatment and the length of the particles may shrink to l / 3rd, i.e. 33.3 pm. The diameter of the cut section may increase accordingly, as the mass of the cut section remains constant. This effect can be used, e.g., to produce lengths that would otherwise not be possible or to reduce the dispersion of lengths.

[0456] An air stream loaded with the pre-cursor particles may be led away from the cutting chamber 112 and fed to a cyclone or another suitable component to separate the precursor particles and air from each other.

[0457] The so-called "Downer Reactor" is known from the literature, in which plastic powder is dispersed in gas so that an aerosol is formed. The aerosol stream is fed into a tubular container and heated so that the particles melt and begin to approach a spherical shape due to the surface tension. It is also known from the literature that these reactors may have a problem that the reactor walls are clogged with powder, so that the yield is significantly reduced and continuous operation over several hours or days may not be possible.

[0458] In embodiments of the present invention, the pre-cursor particles may be dispersed onto a conveyor belt 210 and transported on the conveyor belt 210 through a continuous furnace 204. The temperature in the furnace 204 may be selected so that the pre-cursor particles melt, at least in part. Depending on the viscosity and surface tension of the material of the pre-cursor particles, and the initial shape of the pre-cursor particles, different particle shapes may be created during the process. As the pre-cursor particles lie on the conveyor belt 210, a characteristic flattened side of the particles can be created. The resulting particles then constitute the processed plurality of particles.

[0459] Overall, embodiments of the present technology thus relate to a powder that may exhibit improved characteristics such as flowability and bulk density, as relevant to additive manufacturing properties, and to methods and systems for manufacturing the powder. Whenever a relative term, such as "about", "substantially" or "approximately" is used in this specification, such a term should also be construed to also include the exact term. That is, e.g., "substantially straight" should be construed to also include "(exactly) straight".

[0460] Whenever steps were recited in the above or also in the appended claims, it should be noted that the order in which the steps are recited in this text may be accidental. That is, unless otherwise specified or unless clear to the skilled person, the order in which steps are recited may be accidental. That is, when the present document states, e.g., that a method comprises steps (A) and (B), this does not necessarily mean that step (A) precedes step (B), but it is also possible that step (A) is performed (at least partly) simultaneously with step (B) or that step (B) precedes step (A). Furthermore, when a step (X) is said to precede another step (Z), this does not imply that there is no step between steps (X) and (Z). That is, step (X) preceding step (Z) encompasses the situation that step (X) is performed directly before step (Z), but also the situation that (X) is performed before one or more steps (Yl), ..., followed by step (Z). Corresponding considerations apply when terms like "after" or "before" are used.

[0461] While in the above, preferred embodiments have been described with reference to the accompanying drawings, the skilled person will understand that these embodiments were provided for illustrative purpose only and should by no means be construed to limit the scope of the present invention, which is defined by the claims.

Claims

Claims1. A powder for use in an additive manufacturing process, wherein the powder comprises a processed plurality of particles, wherein each of the processed plurality of particles comprises a particle, wherein a surface of the particle comprises, at least in part, a substantially curved face, and wherein a ratio of a surface area of the substantially curved face to a total surface area of the particle is less than 1, preferably less than 0.95, further preferably less than 0.9.

2. The powder according to the preceding claim, wherein a maximum extension of the particle in any dimension is 200 pm, preferably 100 pm, further preferably 50 pm.

3. The powder according to any of the preceding claims, wherein the particle comprises a substantially flat face.

4. The powder according to the preceding claim, wherein the substantially curved face defines a boundary of the particle in a direction, at least significantly, parallel to a normal to the substantially flat face.

5. The powder according to any of the 2 preceding claims, wherein a cross-section of the particle in a plane, at least substantially, parallel to the substantially flat face is generally elliptical.

6. The powder according to any of the preceding claims, wherein the processed plurality of particles constitutes a majority of the plurality of particles.

7. A method for manufacturing a powder for use in an additive manufacturing process, wherein the powder comprises a plurality of particles, and wherein the method comprises producing each of a processed plurality of the plurality of particles from each of a plurality of pre-cursor particles.

8. The method according to the preceding claim, wherein producing each of the processed plurality of particles comprises melting, at least in part, each of the plurality of pre-cursor particles, and wherein the method comprises arranging each of the plurality of pre-cursor particles on a substantially flat surface before melting.

9. The method according to any of the 2 preceding claims, wherein each of the plurality of pre-cursor particles comprises a section of a filament, wherein the method comprises cutting the filament, wherein cutting the filament comprises guiding the filament through a channel, the channel defined by a feed end, corresponding to an end from which the filament enters the channel, and a cutting end, corresponding to an end out of which the filament exits the channel, wherein the method comprises cutting the filament with a blade, wherein cutting the filament comprises sliding the blade over the cutting end, and wherein the method comprises producing a cut plurality of the plurality of pre-cursor particles,wherein producing the cut plurality of the plurality of pre-cursor particles comprises cutting a plurality of filaments.

10. The method according to the preceding claim, wherein cutting the plurality of filaments comprises guiding a first guided plurality of the plurality of filaments through a first channel and a second guided plurality of the plurality of filaments through a second channel, wherein each of the first and the second channels is defined by a feed end, corresponding to an end from which the first and second guided plurality of filaments enters the channel, and a cutting end, corresponding to an end out of which the first and second guided plurality of filaments exits the channel respectively.

11. The method according to any of the claims 7 - 10, and with the features of any of the 2 preceding claims, wherein guiding through the channel(s) comprises guiding by means, at least in part, of a fluid flow.

12. The method according to the preceding claim, wherein guiding through the channel(s) comprises establishing a lower pressure at the cutting end than at the feed end.

13. The method according to any of the claims 7 - 12, wherein the powder comprises a powder according to any of the claims 1 - 6.

14. A system for manufacturing a powder for use in an additive manufacturing process, wherein the powder comprises a plurality of particles, wherein the system is configured to produce each of a processed plurality of the plurality of particles from each of a plurality of pre-cursor particles.

15. The system according to the preceding claim, wherein the powder comprises a powder according to any of the claims 1 - 6.

16. Use of the powder according to any of the claims 1 - 6 in an additive manufacturing process.

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