A method and system for 3D printing, as well as a spool provided with a filament of a polymeric material for use in the method

Abstract

A system (1) for performing a fused deposition modelling process, the system comprising 1) a printhead comprising a nozzle (6) for expelling fusible polymeric material (7) through the nozzle onto a support (9) while forming a 3D object (8), the polymeric material having a Young's Modulus above 12 GPa at room temperature, 2) a spool (2) having wound thereon a continuous length of a filament of the said polymeric material and 3) an extruder (4) positioned downstream of the spool and upstream of the printhead, for controlling a supply of the filament towards the printhead, wherein the filament is shaped in the form of a tape. The disclosure also pertains to a method using this system and a spool having wound thereon a filament of a polymeric material for use in the system and method.

Description

[0001] A METHOD AND SYSTEM FOR 3D PRINTING, AS WELL AS A SPOOL PROVIDED WITH A FILAMENT OF A POLYMERIC MATERIAL FOR USE IN THE METHOD

[0002] GENERAL FIELD OF THE INVENTION

[0003] The invention in general pertains to the art of 3D printing, also known as additive manufacturing, and in particular to the technology called fused deposition modeling (FDM). FDM is a form of 3D printing technology that falls under the general process of material extrusion. A typical system for FDM comprises 1) a printhead comprising a nozzle for expelling fusible polymeric material through the nozzle onto a support while forming a 3D object, 2) a spool having wound thereon a continuous length of a filament of the said polymeric material and 3) an extruder positioned downstream of the spool and upstream of the printhead, for controlling a supply of the filament towards the printhead. The printhead thus being able to expel a continuous stream of fusible polymeric material on the support. The invention in particular pertains to an FDM process wherein a polymeric material is used having a very high modulus.

[0004] These types of processes typically use a thermoplastic material that is heated to a malleable state and then deposited onto a build plate or printer bed (i.e. the support) in a layer-by-layer process. Fused Deposition Modeling is sometimes referred to as Fused Filament Fabrication (FFF), where the latter term often is associated with 3D printers that are less expensive and intended for hobbyists / home use, while the FDM technology is more often affiliated with industrial production machines. Another distinction between these two terms concerns the printer chamber design - FDM machines typically utilized printer chambers that were heated whereas FFF printers omitted this feature as a means to offer a lower-cost design. However, distinctions between the two terms FDM and FFF have blurred considerably over time, whereby in many instances they essentially refer to the same underlying process wherein an extruded line of a fusible polymer material is deposited on a support to build up an object. Typical materials used in such 3D printing are polymeric materials. Choosing the right polymeric material that results in an object with desired properties, in particular and basically meeting at least a predetermined minimum mechanical strength is key in the design of an adequate 3D printing process. The present invention in particular enables to use polymer materials with higher intrinsic strength. BACKGROUND OF THE INVENTION

[0005] 3D printing can create physical objects from a geometrical representation by successive addition of material. The 3D printing process was first commercialised in the year 1980 by Charles Hull but has experienced a phenomenal expansion in recent years. Currently, 3D printing is for example used for producing artificial heart pumps, jewellery, producing cornea, parts for rocket engines, airplanes, buildings and other products related for example to the aviation industry as well as the food industry. 3D printing technology has originated from the layer-by-layer fabrication technology of three- dimensional structures directly from computer-aided design (CAD) drawings. 3D printing technology is a truly innovative and has emerged as a versatile technology stage. It opens new opportunities and gives hope to many possibilities for companies looking to improve manufacturing efficiency.

[0006] Conventional polymeric (e.g. thermoplastic and thermoset materials with or without any fillers) materials, ceramics, graphene-based materials, and metals are the materials that can be printed now by using 3D printing technology. 3D printing technology has the potential to revolutionise industries and change production methods. The adoption of 3D printing technology will increase the production speed while reducing costs. At the same time, the demand of the consumer will have more influence over production. Consumers have greater input in the final product and can request to have it produced to fit their specifications. At the meantime, the facilities of 3D printing technology will be located closer to the consumer, allowing for a more flexible and responsive manufacturing process, as well as greater quality control. Furthermore, when using 3D printing technology, the need for global transportation is significantly decreased. This is because, when manufacturing sites located nearer to the end destination, all distribution could be done with fleet tracking technology that saves energy and time. Lastly, the adoption of 3D printing technology can change the logistics of any company. Nowadays, 3D printing is widely used in the world. 3D printing technology increasingly used for the mass customization, production of any types of open-source designs in the field of agriculture, in healthcare, automotive industry, and aerospace industries. To sum up, 3D printing technology has emerged during recent years as a flexible and powerful technique in the advanced manufacturing industry.

[0007] Varieties of 3D printing technologies have been developed, fused deposition technology being one of them. This technology uses polymeric materials, in particular thermoplastic materials, for manufacturing an object by depositing layers of liquid material (meaning at least being fusible when deposited) on top of each other, typically in the form of individual droplets or filaments (bot referred to as “beads” in the art of 3D printing) and therewith form the desired object. By using fused deposition modelling, a 3D object can be printed through the deposition of successive layers of contiguous distinct droplets or extruded thermoplastic filaments. Typical polymers used for the polymeric materials for use in 3D printing technology are polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PETG), acrylonitrile styrene acrylate (ASA), Polyamide 6, PA6.66, PA66.6, PA11 and PA12 polypropylene (PP) or polyethylene (PE). Lately, thermoplastics filaments with higher melting temperatures and higher moduli (potentially improved by adding fibres) such as polyether ether ketone (PEEK) (or other members of the peak family such as PEAK, PEKK, PEK and semi crystalline forms thereof), polyphtalamide (PPA), polyketone (PK), poly(p-phenylene oxide) (PPO OR PPE), poly ether imide (PEI), polyimide (PI), polyphenylene sulfide (PPS), polyethersulfone (PESU), polysulfone (PES) and polymethyl methacrylate (PMMA) are used as materials for 3D printing technology.

[0008] For reliable 3D printing of polymeric materials with sufficient speed, continuous filaments of the polymeric material are used for supply of the material to the printhead, wherein the filaments have a length of at least 100 meters (typically 200-500 m), and a diameter of about 1.5 to 2 mm. The continuous length is needed in order to make sure the printing process is not interrupted. Although a higher thickness would be advantageous since more material can be supplied per length of filament, this is often not possible since the filament is wound on a spool. Too thick filaments cannot be wound without the risk of breaking. Also, the polymeric material may have a Young’s modulus that is too high for allowing winding of this filament on a spool. This means that at this moment, ultra strong polymer materials, e.g. fibre-filled PEEK, cannot be used in a high quality industrial FDM processes that relies on a continuous supply of a filament from a spool. A solution that is used is to use an unfilled high modulus polymeric material, and co-extrude a continuous fibre into the filament just before the printhead. This may indeed serve to reach certain mechanical properties that are higher than based on the polymeric material alone, but the effect is minimal at the cost of a more complicated printing process, needing co-extrusion and the cutting of the fibres after each stretch of deposited material. It is thus commonly accepted that for obtaining 3D printed objects that need to have a very high strength, other materials that polymeric material must be used, typically metals.

[0009] OBJECT OF THE INVENTION

[0010] It is an object of the invention to make it easier to used high modulus polymeric materials in a typical fused deposition modelling process.

[0011] SUMMARY OF THE INVENTION

[0012] In order to meet the object of the invention a system for performing a fused deposition modelling process as described in the General Field of the Invention section here above has been devised, wherein the polymeric material has a Young’s Modulus above 12 GPa at room temperature, wherein the system is altered in that the filament (thus as wound on the spool) is shaped in the form of a tape.

[0013] In hindsight this may look like a small and insignificant change, but it is not. Firstly, it has to be recognised that in practice, all filaments used in FDM have a circular cross section. This is because it is easier to produce an even circular shaped filament (evenness of the filament is of the utmost importance for a high quality FDM process), than any other form. Next to this, since most FDM printheads move with respect to the support during printing, it is an advantage that the filament can be bend in all directions using the same force. Apparently, because of all of this, in practice no one has ever considered a shape for a filament for use in FDM hat is completely non circular.

[0014] However, several insights led to the present alteration to use a filament that has the shape of a tape, and was found to be very advantageous, in particular when desiring to print a polymeric material having a very high intrinsic strength, i.e. a Young’s modulus above 12GPa at room temperature. When shaping the filament as a tape, a tape can be used that is very thin, e.g. 0.5 mm and thus easy to wind on a spool even when the Young’s modulus is very high, while ensuring a sufficiently large cross section (needed to arrive a reasonable printing speeds) by having a large width such as 4-10 mm. Another advantage is that the tape can be used as is, for re-enforcing any printed object by applying the tape in a direction of layering (i.e. perpendicular to the direction in which one single layer is printed), to the printed object.

[0015] When being in the form of a tape, it was found that polymeric materials with a Young’s modulus of up to at least 30 GPa could be printed, whereas in the art, the maximum is about 12 GPa, at least when using continuous filaments wound on a spool. Thus, the invention opens the way to printing objects using continuous filaments having the strength of metals, albeit by using polymeric materials and thus saving a substantial amount of weight. This is in particular advantageous for any object that is, or is part of an object designed for travelling through the air.

[0016] It is noted that high strength polymeric materials for 3D printing are known in the art, but these are supplied to the printhead discontinuously (e.g. in the form of blocks, short rods, beads etc.), or in the form of vert thin filaments, both of which measures are disadvantageous to arrive at a high quality and / or high speed FDM process.

[0017] It is also noted that the exact dimensions of the tape (thickness vs width) are not essential for the invention. The gist is that when starting form a particular state of the art filament needed for a particular 3D printer, the option is now provided to print polymeric materials of considerably higher strength, by shaping the filament in the form of a tape, i.e. being considerably thinner than the original filament, but wider (keeping the cross section at the same level), allowing the stronger material to be wound on the spool without the risk of breaking.

[0018] Producing a filament in the form of a tape that has a very even cross section may be more difficult than a circular filament, but it is possible using art known methods (e.g. magnetic tape for sound and video recorders). Also, if the fact that the tape cannot be bend in all directions using the same force is a problem in a particular printer, it is an option to use a die in the extruder (which is warm enough to re-shape the filament) that expels the heated filament having a (more or less) round cross section. In other words, the disadvantages of a non round shape can be easily overcome if needed.

[0019] The invention is also embodied in a method to print a 3D object using a system as defined here above, the method comprising unwinding the spool to supply the filament having the shape of a tape to the extruder, supply the filament to the printhead, heating the filament to provide the polymeric material in a fusible form and expelling the fusible polymeric material through the nozzle of the printhead onto a support to form the 3D object.

[0020] Lastly, the invention is embodied in a spool having an outer diameter of at most 50 cm (typically 20-30 cm; the size of spool for most commercial FDM printers), having wound thereon a filament of the polymeric material as defined here above, the filament having a length of at least 10 metres, preferably at least 100 metres, the filament being in the form of a tape and having a thickness of at most 1.5 mm.

[0021] DEFINITIONS

[0022] A polymeric material is a material which comprises as a main component a polymer, thus at least over 50% w / w. The polymer content may be higher, for example 55, 60, 65, 70, 75, 80, 81 , 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 up to even 100% w / w. However, the material may comprise other compounds such as fillers, stabilisers, dispersant, flame retardation compounds, conductivity enhancers, pigments etc.

[0023] 3D printing is a form of additive manufacturing wherein molten material is deposited on a support, layer by layer, to ultimately form an object of fused elements of this material. The elements may be deposited in the form of droplets, filaments, ribbons etc.

[0024] A filament is a thin thread or thread-like structure.

[0025] A tape is a long, narrow strip of a thin material, of which the ratio between thickness and width is at least 1:2, preferably at least 1 :3 or even 1 :4, 1 :5, 1 :6, 1 :7, 1 :8, 1 :9, 1 :10, up to for example 1:100. It is in essence flat, although it is not excluded that its opposing flat surfaces are convex, concave, profiled or have irregularities such as dents, scratches, bulges etc, and the edges of the tape may be rounded. A tape typically has a rectangular shape.

[0026] Roundness at a cross section of an object is defined as the ratio of the surface area of the cross section of the object to the area of the circle whose diameter is equal to the maximum diameter of the cross section. A perfect circle has a roundness of 1, a square has a roundness of 0.7 and an octagon has a roundness of 0.92.

[0027] Continuous in the sense of the present invention means being uninterrupted on a scale exceeding multiple metres, in particular over 5 or evenlO metres, especially over 100 metres up to for example 200, 500 or even 1000 metres.

[0028] The Young’s modulus, also referred to as E modulus or Tensile modulus, is the ratio of the stress (force per unit area) applied to a solid material and the resulting axial strain (displacement or deformation) in the linear elastic region of the material. The Young’s modulus can be determined according to ISO 527-1 / -2.

[0029] The Tensile Strength of a material is the maximum load that this material can support without fracture when being stretched, divided by the original cross-sectional area of the material. Like the Young’s modulus, it can be determined using ISO 527-1 / -2.

[0030] An extruder \s a machine that extrudes (forces out) a material, optionally through a die for re-shaping the material. An extruder may have various separate sub-sections that are operatively connected to each other such that a material is extruded in various subsequent parts of the machine. An extruder may have means to heat the material in order to increase the malleability of the material.

[0031] Automatically means without needing human operator intervention. Automatically does not exclude that the corresponding process is operator initiated or stopped, as long as there is no human operator needed to perform the process as such.

[0032] FURTHER EMBODIMENTS OF THE INVENTION

[0033] In a first further embodiment of the system according to the invention, the system is constituted to supply the polymeric material to the nozzle in the form of a re-shaped filament having a cross section with a roundness of at least 0.7 (e.g. 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79), preferably at least 0.8 (e.g. 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88 or 0.89), preferably at least 0.9 (e.g. 0.90, 0.91 , 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 up to 1.0) when entering the nozzle. This embodiment has the advantage that the printhead expels the filament in a shape that is comparable to a prior art printer such that it can be easily adapted to be used in a prior art printer. For example, it is possible to re-shape the filament in the extruder, such that the filament is supplied to the printhead with a circular cross section. This has the advantage that the printhead can easily move in any direction with respect to the extruder with a low risk of breaking the filament, given the fact that its cross section is in essence circular. This means that the invention can also be applied in FDM printers wherein the printhead moves with respect to the extruder. However, it is also foreseen that the re-shaping does not take place until the filament is present in the printhead.

[0034] In another embodiment of the system according to the invention, the filament has dimensions such that its width (i.e. the dimension in the axial direction of the spool) is between 1.5 and 10 mm (e.g. 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5 or 10 mm), and its thickness (i.e. the dimension in the radial direction of the spool) is between 0.2 and 1.5 mm (e.g. 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4 or 1.5 mm). These dimensions have been found to be ideally suitable for the most common range of FDM printers. Preferably, the filament has dimensions such that its width is between 2.0 and 5.0 mm, and its thickness is between 0.5 and 1.5 mm. If the dimensions are chosen such that the cross section of the tape is equal to the cross section of a prior art circular filament (typically around 2.4 mm2for a filament with a diameter of 1.75 mm), the tape can be used in the same type of FDM system since the volume throughput per mm of filament length is the same.

[0035] In yet another embodiment of the system according to the invention, the polymeric material has a Young’s Modulus above 12 GPa at room temperature (e.g. 13, 14, 15, 16, 17, 18, 19, 20 GPa) and preferably a Tensile Strength above 120 mPa at room temperature. It was found that the invention is ideally suitable for such high strength polymeric materials, in particular even when the polymeric material has a Young’s Modulus above 20 GPa at room temperature (such as 21, 22, 23, 24, 25), or even above 25 GPa at room temperature (e.g. 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40 or above).

[0036] In still another embodiment of the system according to the invention, the polymeric material is has dispersed therein strengthening fibres that have a length below the smallest dimension of the filament. By adding short fibres to the polymeric material, the strength (moduli) may increase substantially, and hence the strength of the ultimate 3D printed object. Still, in the art this is hardly ever done given the problem of breaking the filament when winding it on a spool, unwinding it therefrom, or using it in a printer. However, with the current invention of having the filament in the form of a tape, adding short fibres is no problem whatsoever. Preferably, the fibres dispersed in the polymeric material extend in the length direction of the filament and have a length less than 1.0 mm, preferably less than 0.5 mm, for example in the range of 1x102- 4x102pm. This way the printing process is not disturbed by the presence of the fibres while still enabling the modeling of a very strong 3D printed object. Typical fibre length is 200-300 pm with a thickness of 6 pm. Optionally, if desired such fibres can be combined with a continuous fibre as described here above.

[0037] In again another embodiment of the system according to the invention, the system further comprises a unit (such as a robot arm) to automatically fuse a (for example precut) length of the filament (which may be cut form a filament wound on another spool, or cut before or after object is printed from a filament that is on the same spool, or in any other way) to a surface of the 3D object. The inventors recognized that a printed object may relatively weak in certain directions despite using a high strength polymeric material. For example, when printing an object by layering beads on top of each other in the vertical (Z) direction, the strength in this layering (Z) direction is determined mainly by the fusing of various contiguous layers, and less by the inherent strength of the material. Since there is a filament available in the form of a tape, this tape can be applied on the object, extending in the Z direction, and fused thereto, this way substantially improving the strength of the object in this direction. Such application of a length of tape and fusing can be accomplished easily automatically, e.g. using a robot having an induction or laser head for heating the surface of the filament and / or object.

[0038] The above further embodiments also lead to corresponding embodiments of the method according to the invention. In particular, in a further embodiment of the method according to the invention, the filament is reshaped such that it is leaves the extruder while being supplied to the printhead having a cross section with a roundness of at least 0.8, preferably at least 0.9.

[0039] In another embodiment of the method, a length of the filament is automatically fused to a surface of the 3D object. Preferably, the length of the filament fused to the 3D object extends in a direction in which the polymeric material is layered in the 3D object (the Z direction).

[0040] Further embodiments of the spool according to the invention are a spool wherein the polymeric material has a Young’s Modulus above 12 GPa at room temperature and preferably a Tensile Strength above 120 mPa at room temperature, preferably wherein the polymeric material has a Young’s Modulus above 20 GPa at room temperature, preferably above 25 GPa at room temperature.

[0041] Next to this, a preferred embodiment of a spool according to the invention is characterised in that the filament has dimensions such that its width is between 2.0 and 5.0 mm, and its thickness is between 0.5 and 1.5 mm. This spool corresponds to spools typically used in contemporary high quality industrial FDM printers.

[0042] The invention will now be further explained using the following particular examples.

[0043] EXAMPLES

[0044] Figure 1 is a schematic representation of an FDM system as known in the art.

[0045] Figure 2 is a schematic representation of an FDM system according to the invention.

[0046] Figure 3 is a schematic representation of parts of an alternative FDM system.

[0047] Figure 4 shows the spool of figure 2 in more detail.

[0048] Figure 5 shows an object printed with a system according to the invention.

[0049] Example 1 is an example of printing an 3D object using the system and method according to the invention.

[0050] Figure 1

[0051] Figure 1 is a schematic representation of an FDM system 1 as known in the art, for printing high quality objects. A spool 2 on which a filament 3 of a polymeric material is wound is first fed towards the FDM printhead, comprising heater block 5 and nozzle 6. The nozzle typically has a small diameter of about 0.6 mm. However, larger nozzles may be useful in case a higher output speed is necessary. The filament 3 is fed into an extruder 4, which uses a gear and a bearing to control the flow of filament into the heated block 5 and nozzle 6. Once the heating block reaches the correct temperature, the filament is fed into the nozzle and is further heated by this nozzle (corresponding to the process in a glue gun, but with filament instead of hot glue). The material 7 in fusible form is extruded (or “drawn”) onto the build platform 9 (acting as a support) in the x-y plane, where it quickly cools into the desired cross-sectional shape 8. The printhead crosses the platform in x-y plane and adjusts vertically (on the z-axis) so that another layer can be placed on top of the previous layer, and the process repeats until the printer has completed the object (not shown as a complete part in figure 1). This entire assembly is directed and controlled via a controller board, or a microprocessor that handles the x-y-z movement, temperature regulation, and software integration for the FDM printer as is commonly known in the art

[0052] Figure 2

[0053] Figure 2 is a schematic representation of an FDM system T according to the invention. The system differs from the one shown in figure 1 in that the filament 3a has the form of a tape (see figure 3 for details), and in that the extruder is composed of two separate parts 4a and 4b. In part 4a the filament 3a is heated and re-shaped to become more circular (attaining a higher roundness). It leaves the first part 4a and is fed as a reshaped filament 3b to the second part of the extruder 4b, where the filament is further heated and re-shaped to attain a roundness of 0.95, to become further re-shaped filament 3c. The basic FDM process thereafter for producing the object 8 is the same as indicated in figure 1.

[0054] Next to the above, the novel system in this embodiment also comprises a robot 10, which has an arm 11 for the precise placement of parts onto the object 8 after the basic FDM process. Such a part may be a pre-cut length of the filament 3a. The robot 10 also comprises a laser arm 12 for locally heating the polymeric material, such that the filament can be fused to the object. This is shown in more detail in figure 5.

[0055] Figure 3

[0056] Figure 3 shows basic parts for an alternative FDM system. In figure 3A the extruder 4 and heated block 5 with nozzle 6 are shown, through which elements tape shaped filament 3 is transported, and ultimately melted in block 5 to be expelled in liquid (paste) form from nozzle 6 (having a diameter of 0.4 mm in this case). In the extruder the filament may be pre-heated but is not yet re-shaped, it keeps its tape form. In heated block 5 there is a reducer part 55, which at its entrance 56 is formed to accommodate the tape shape (see figure 3B for more detail), and at its outlet 57, i.e. at the entrance of the nozzle 6, is formed to produce a circular filament with a roundness of around 0.95 or more. This reducer piece can be used in a more or less standard heated block to be able and apply the current invention. Figure 3B shows the reducer in more detail.

[0057] A concomitant advantage of the invention is that a tape can be heated more quickly than a circular filament because of its reduced thickness (when compared to a circular filament having the same cross section). This means that with a filament in the form of a tape, printing can be done faster. This is in particular noticeable for materials that are high in crystallinity which need a lot of energy to melt.

[0058] Figure 4

[0059] Figure 4 shows the spool 2 of figure 2 in more detail. In particular, it can be seen that the filament 3a has a thickness T of 0.75 mm and a width W of 3.2 mm. This way the cross section has a surface of 2.4 mm2, which is equal to the surface of a typical circular filament having a diameter of 1.75 mm. In this schematic representation the edges of the tape are right corners. However, in practice they are slightly rounded to meet the shape of the entrance 56 of reducer 55 as shown in figure 3B.

[0060] Figure 5

[0061] Figure 5 shows an object 8, printed using the system of figure 2, and being provided with three strips of the filament 3a, fused to the surface of the 3D object 8. Each of the lengths, which may be pre-cut or cut by the unit right after printing, is fused to the object 8 such that it extends in the Z-direction, i.e. the direction in which the polymeric material is layered in the object. This way the strength of the object in this direction is substantially improved.

[0062] Example 1

[0063] Example 1 is an example of printing an 3D object using the system and method according to the invention, wherein a 3D object is printed using a 30% carbon fibre filled PEEK (available e.g. from Victrex Pic, Lancashire), having a Young’s modulus of 28 GPa and a Tensile strength of 265 MPa. By providing the material in the form of a tape as indicated in figure 3, the filament can be provided wound on a standard spool with a diameter of 20 cm, and a core of 5 cm, without a substantial risk of breaking this highly rigid material. The length of the filament is about 320 metres, enough to print relatively large objects without any discontinuity in the supply. Comparable results are obtainable with a 30% carbon fibre filled PP, a 20% carbon fibre filled PA11 and a 15% carbon fibre filled rPEEK.

[0064] This spool when loaded in the system of figure 2 is used to print a high strength object of this material, in this example a body part of a drone.

Claims

CLAIMS1. A system for performing a fused deposition modelling process, the system comprising:- a printhead comprising a nozzle for expelling fusible polymeric material through the nozzle onto a support while forming a 3D object, the polymeric material having a Young’s Modulus above 12 GPa at room temperature;- a spool having wound thereon a continuous length of a filament of the said polymeric material;- an extruder positioned downstream of the spool and upstream of the printhead, for controlling a supply of the filament towards the printhead; characterised in that the filament is shaped in the form of a tape.

2. A system according to claim 1, characterised in that the system is constituted to supply the polymeric material to the nozzle in the form of a re-shaped filament having a cross section with a roundness of at least 0.7, preferably at least 0.8 and more preferably at least 0.9 when entering the nozzle.

3. A system according to any of the preceding claims, characterised in that the filament has dimensions such that its width is between 1.5 and 10 mm, and its thickness is between 0.2 and 1.5 mm, preferably in that the filament has dimensions such that its width is between 2.0 and 5.0 mm, and its thickness is between 0.5 and 1.5 mm.

4. A system according to any of the preceding claims, wherein the polymeric material preferably has a Tensile Strength above 120 mPa at room temperature, charactersied in that the Young’s Modulus is above 20 GPa at room temperature, or even above 25 GPa at room temperature.

5. A system according to any of the preceding claims, characterised in that the polymeric material is has dispersed therein strengthening fibres that have a length below the smallest dimension of the filament.

6. A system according to claim 5, characterised in that the fibres dispersed in thepolymeric material extend in the length direction of the filament and have a length less than 1.0 mm, preferably less than 0.5 mm.

7. A system according to any of the preceding claims, characterised in that the system further comprises a unit to automatically fuse a length of the filament to a surface of the 3D object.

8. A method to print a 3D object using a system according to any of the preceding claims, the method comprising:- unwinding the spool to supply the filament having the shape of a tape to the extruder;- supply the filament to the printhead;- heating the filament to provide the polymeric material in a fusible form;- expelling the fusible polymeric material through the nozzle of the printhead onto a support to form the 3D object.

9. A method according to claim 8, characterised in that in the extruder and / or printhead, the filament is reshaped such that it is supplied to the nozzle having a cross section with a roundness of at least 0.7, preferably at least 0.8, more preferably at least 0.9.

10. A method according to any of the claims 8 or 9, characterised in that a length of the filament is automatically fused to a surface of the 3D object.

11. A method according to claim 10, characterized in that the length of the filament fused to the 3D object extends in a direction in which the polymeric material is layered in the 3D object.

12. A spool having an outer diameter of at most 50 cm, having wound thereon a filament of a polymeric material, the polymeric material having a Young’s Modulus above 12 GPa at room temperature, the filament having a length of at least 10 metres, the filament being in the form of a tape and having a thickness of at most 1.5 mm.

13. A spool according to claim 12, characterised in that the polymeric material has a Tensile Strength above 120 mPa at room temperature.

14. A spool according to claim 13, characterised in that the polymeric material has a Young’s Modulus above 20 GPa at room temperature, preferably above 25 GPa at room temperature.

15. A spool according to any of the claims 12 to 14, characterised in that the filament has dimensions such that its width is between 2.0 and 5.0 mm, and its thickness is between 0.5 and 1.5 mm.

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