Heat Treatment of 3D Printed Parts

Abstract

The present invention relates to a device 100 for surface treatment of 3D printed parts for bioprocessing equipment. The device 100 includes a surface refinishing tool 110 including a contact surface 116, the contact surface 116 including a negative shape of a surface to be treated of the 3D printed part. The device 100 also includes a heating device 120 operable to heat the surface refinishing tool 110 to a temperature above a melting temperature of a material of the 3D printed part. The device 100 also includes an actuator 130 operable to move the surface refinishing tool 110 such that the surface refinishing tool 110 can be releasably pressed against the surface to be treated to melt said surface and form a melted layer of said material on said surface. The device 100 further includes a cooling device operable to cool the surface refinishing tool 110 and thereby resolidify the melted layer of said material on said surface to form a treated surface.

Description

[Technical field]

[0001] The present invention relates generally to post-processing of 3D printed parts for bioprocessing equipment. More particularly, the present invention relates to devices and methods for surface treating 3D printed parts using heat to improve the surface finish of said 3D printed parts. [Background technology]

[0002] 3D printing technology, also known as additive manufacturing, has been around since the 1980s, when it was first used for rapid prototyping for product development in several industries. However, it is only in the past decade that the true potential of this technology has been realized. Currently, 3D printing technology is used in a variety of technology fields to manufacture a wide variety of objects, including household items, toys, clothing, tools, machine and industrial parts, human tissue, and more.

[0003] 3D printing technologies offer enhanced design freedom and allow for greater dimensional control over traditional manufacturing techniques such as injection molding and die casting, enabling highly complex structures to be produced precisely and repeatably.

[0004] Two widely used 3D printing techniques are fused deposition modelling (FDM) and selective laser sintering (SLS). In the FDM technique, a thermoplastic filament is heated to its melting point and then extruded layer-by-layer onto a build platform to generate a three-dimensional object. On the other hand, SLS is a powder-based manufacturing technique that uses a laser beam to selectively shape particles of a thermoplastic polymer powder laid down on a powder bed and fuse them together to build a part layer-by-layer.

[0005] In general, one problem associated with many 3D printed objects is that they usually have a rough surface and therefore require some form of post-processing to achieve the required surface finish. Objects printed using FDM technology generally exhibit a pronounced stair-stepping effect, where traces of the layers are clearly visible. One solution to overcome this problem is to reduce the layer height, but this significantly increases the build time. Longer printing times can cause distortion and filament clogging. Similarly, objects printed using SLS technology suffer from the problem of partially melted powder particles sticking to the surface, thus making it rough.

[0006] The problem of poor surface finish of 3D printed parts has made the adoption of 3D printing technology difficult, especially in the manufacture of parts for bioprocessing equipment. Poor surface finish is particularly problematic when the bioprocessing equipment parts are mating parts, or similarly when they are intended for use with wetted components that need to provide adequate sealing function. Such parts include, but are not limited to, connectors, valves, and adapters used to interconnect various components such as chromatography columns, filtration units, dispensing units, and tubing in bioprocessing systems.

[0007] Some of the known post-processing methods include tumbling, water jetting, sanding, chemical dip cleaning, coating, polishing, and bead blasting. The amount of post-processing required depends on several factors, including but not limited to the size of the part, the intended application, and the type of 3D printing technology used for the product.

[0008] Some methods of post-treatment involve the application of heat, such as ironing, heated isostatic pressing (HIP), and hot gunning. Ironing involves depositing a thin layer of thermoplastic polymer filaments onto the surface to be smoothed. However, this process is extremely time consuming and therefore significantly increases the overall build time without resulting in a very good surface finish. Melting rough surfaces using a hot gun or flame torch is another known heat-based post-treatment method commonly used by amateurs and hobbyists. However, this method produces very uneven melting on the surface being treated, resulting in shape deformation and melting away of thin and delicate areas if the operator is not careful enough. Again, this method poses significant safety concerns since it uses an open flame.

[0009] Although the above-mentioned post-processing methods are deemed satisfactory in some applications, they fail to provide the desired degree of surface finish for 3D printed parts used in bioprocessing equipment. Insufficient surface finish achieved using one or more of the above methods may result in surfaces that are not suitable as sealing surfaces in bioprocessing systems, thereby making the systems prone to leaks. Fluid leakage is highly undesirable in bioprocessing facilities, as it can lead to loss of valuable biological products, such as antibodies and other cell therapy products, as well as cause contamination of the surrounding environment if the biological product is, for example, a virus-containing solution.

[0010] Another problem that can arise is sticking, where increased mating / release forces are required to connect / disconnect the part to other parts within the bioprocessing system due to friction between poorly finished surfaces of the parts. The use of increased forces can also cause disturbances that can damage delicate cell-based products being handled within the system as well as the surrounding bioprocessing equipment. Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, there is a need for devices and methods that provide excellent surface finishes on 3D printed parts to make them suitable for bioprocessing equipment. [Means for solving the problem]

[0012] Therefore, there is provided the invention as defined by the appended claims.

[0013] Various aspects and embodiments of the present invention are defined by the following claims.

[0014] According to a first aspect, the present invention provides a device for surface treatment of 3D printed parts for bioprocessing equipment, such as chromatography systems, filtration systems or aseptic filling systems, whereby a high surface finish is achieved on the treated surface (the surface to be treated).

[0015] The device includes a resurfacing tool including a contact surface, the contact surface including a negative shape of a to-be-treated surface of the 3D printed part. In one embodiment of the invention, the resurfacing tool includes one or more internal fluid channels.

[0016] The device also includes a heating device operable to heat the resurfacing tool to a temperature above a melting temperature of the material of the 3D printed part. In one embodiment of the invention, the heating device includes an externally heated metal block. In another embodiment of the invention, the heating device includes a heating element integral with the resurfacing tool.

[0017] The device further includes an actuator operable to move the surface refinishing tool such that the surface refinishing tool can be releasably pressed against the surface to be treated to melt material of the 3D printed part and form a dissolved layer of said material on said surface.

[0018] The device also includes a cooling device operable to cool the surface refinishing tool, thereby actively resolidifying the melted layer at the treated surface to form a treated surface. The device may also be used to cool the surface refinishing tool prior to removing the surface refinishing tool (e.g., when the plastic material of the 3D printed part has cooled sufficiently such that it does not stick to the surface refinishing tool and maintains its new surface shape). In one or more embodiments of the invention, the cooling device includes a cooling fluid source connected to the surface refinishing tool.

[0019] In one or more embodiments of the invention, the device further includes a plurality of sensors configured to measure at least one process parameter of a surface treatment method being performed in the device, and a control unit configured to control the surface treatment method based on one or more measurement results obtained by one or more of the plurality of sensors.

[0020] According to a second aspect, the present invention provides a method for surface treatment of 3D printed parts for bioprocessing equipment. In one embodiment of the present invention, the method for surface treatment is implemented using a device according to the first aspect of the present invention.

[0021] The process includes heating a surface refinishing tool to a temperature above the melting temperature of a material of the 3D printed part prepared for surface treatment, and pressing the surface refinishing tool against a treated surface of the 3D printed part to melt the surface and form a molten layer of the material on the surface.

[0022] The process further includes ceasing heating of the surface refinishing tool to stop said dissolution, and cooling the surface refinishing tool to resolidify the dissolved layer on the surface, thereby creating a treated surface. In one embodiment of the invention, the cooling step includes flowing a cooling fluid through one or more internal fluid channels of the surface refinishing tool. As the surface refinishing tool is cooled while pressed against the treated surface, the surface finish of the contacting surface of the surface refinishing tool is transferred to the treated surface as the dissolved layer resolidifies. Following this, the surface refinishing tool is released from the treated surface.

[0023] According to a third aspect, the present invention provides a 3D printed part made of a thermoplastic material, said part may comprise at least a part of a surface having a relatively low value of an average surface roughness value Ra. For example, some of such surfaces may have an average Ra that is within the range of less than about 16 μm, less than about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2.4, 2, 1.6, 1.5, or 1 μm, about 0.5 μm, about 0.4, 0.5, or 0.6 μm to about 0.7, 0.8, or 0.9 μm, about 0.7 to about 0.8 or 0.9 μm, and / or about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 μm to about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2.4, 2, 1.6, 1.5, or 1 μm.

[0024] For example, the 3D printed part may be a 3D printed valve whose valve seat surface has an Ra value in the range of low values, such as about 0.7-0.9 μm. The surface refinishing tool may thus be configured to engage with the valve seat portion of the 3D printed part. For example, the surface refinishing tool may be an elongated (e.g., substantially cylindrical) shape having a chamfered annular symmetrical inclined surface provided at one end that engages with the valve seat portion of the 3D printed part. Such surface treatment of the 3D printed part, particularly at any valve seat portion thereof, is advantageous as it allows for reducing any closing force required within the valve to provide an adequate seal, as well as reducing the likelihood of the valve sticking when any such closing force is released.

[0025] In another example, the 3D printed part may be a connector / adapter, the connections of which have surfaces with Ra values ​​in a low or relatively low range, for example, a 3D printed part may be provided having a lower value than is typical in the prior art (e.g., about 16-20 μm less than currently typical Ra for untreated printed surfaces).

[0026] One advantage of the present invention is that the surface roughness of a 3D printed part can be significantly reduced in one or more locations in a repeatable manner.

[0027] Another advantage of the present invention is that 3D printed parts such as connectors and valves can be created without compromising their sealing capabilities, thus making the 3D printed parts suitable for bioprocessing equipment in sterile environments where sealing is essential and critical.

[0028] Another advantage of the present invention is that 3D printed parts processed using the devices and methods of the present invention are highly suitable for use with wetted components in bioprocessing facilities due to their excellent sealing surfaces that make them leak resistant.

[0029] Another advantage of the present invention is that the 3D printed parts can be connected and disconnected without exerting excessive force, therefore making it extremely suitable where delicate therapeutic cells such as biologics are being handled and disturbances may be an issue.

[0030] Yet another advantage of the present invention is that because the surface refinishing tool includes a contact surface that includes a negative shape of the surface being treated, the surface refinishing tool ensures uniform heat transfer to the surface being treated by establishing uniform surface contact, thus resulting in a uniform surface finish.

[0031] Additional benefits and advantages of aspects and embodiments of the present invention will also become apparent to those of ordinary skill in the art upon reading the disclosure provided herein.

[0032] Various aspects and embodiments of the invention are described in more detail below with reference to the accompanying drawings. [Brief description of the drawings]

[0033] [Figure 1] 1 is a cross-sectional view of a device according to a first embodiment of the present invention. [Figure 2A] FIG. 2 is a perspective view of a resurfacing tool for the device shown in FIG. 1. [Figure 2B] FIG. 2 is a cross-sectional view of a resurfacing tool for the device shown in FIG. 1. [Diagram 3] FIG. 2 is a perspective view of the device shown in FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view of a device according to a second embodiment of the present invention. [Diagram 5] 10 is a flow chart illustrating a method for surface treatment of a 3D printed part according to a third embodiment of the present invention. [Figure 6] 1 is a top view of an untreated surface and a surface treated by the surface treatment method of the present invention at 290x magnification. [Figure 7] Scanning electron microscope (SEM) images of cross-sections of small surface-treated samples under five different magnifications.

[0034] List of Tables Table 1 shows the Ra values ​​measured during experiment 1. Table 2 shows the Ra values ​​measured during experiment 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] 1 shows a cross-sectional view of a device 100 for surface treatment of 3D printed parts according to a first embodiment of the invention. The device 100 includes a surface refinishing tool 110, a heating device 120, an actuator 130 and multiple inlet / outlet ports 150.

[0036] The surface refinishing tool 110 includes a contact surface 116, which includes a negative shape of the surface to be treated of the 3D printed part. Because the contact surface 116 includes a negative shape of the surface to be treated, when the surface refinishing tool 110 is pressed against the surface, the contact surface 116 of the surface refinishing tool 110 is assigned to a corresponding positive shape of the surface and contact is established between the contact surface 116 and the surface to be treated. In one embodiment of the present invention, the surface to be treated can be, for example, a valve seat in a 3D printed valve or a connection of a 3D printed connector / adapter. The contact surface 116 can also be optionally shrink compensated depending on the material (e.g., thermoplastic) used in the 3D printed part.

[0037] The refinishing tool 110 comprises a metallic material since metals are good conductors of heat. In this embodiment, copper is used to make the refinishing tool 110. In an alternative embodiment of the invention, the refinishing tool 110 comprises a metallic material including one or more of copper, iron, steel, and aluminum.

[0038] The surface refinishing tool 110 is configured to be releasably pressed against a surface to be treated of a 3D printed part. This is accomplished by operating an actuator 130 connected to the surface refinishing tool 110 to move the surface refinishing tool 110 relative to the surface to be treated. In this embodiment, the actuator 130 includes a cylinder 132 including a piston 134 connected to a piston rod 136. As shown in FIG. 1, the surface refinishing tool 110 is connected to the piston 134 via the piston rod 136. In one example, the cylinder 132 is a pneumatic cylinder operable to linearly move the surface refinishing tool 110 by actuating a first piston 134 in the first cylinder 132.

[0039] The surface refinishing tool 110 is further connected to a heating device 120 configured to heat the surface refinishing tool 110 to a temperature above the melting temperature of the material of the 3D printed part such that the surface to be treated can be melted when the surface refinishing tool 110 is pressed against the surface to be treated. Since the contact surface 116 of the surface refinishing tool 110 is shaped to conform to the surface to be treated, a uniform transfer of heat from the surface refinishing tool 110 to the surface to be treated can be achieved. This helps to achieve a uniform melting of the surface to be treated.

[0040] In one or more embodiments of the present invention, the material of the 3D printed part includes a thermoplastic material, such as polypropylene. Preferably, a relatively dense material is used so that pore sintering of the 3D printed part can be minimized to mitigate shrinkage. Materials such as COC materials can also be used, for example, printed, using FDM techniques.

[0041] In this embodiment, the heating device 120 is in the form of an externally heated metal block configured to be releasably pressed against the surface refinishing tool 110. When the heated metal block is pressed against the surface refinishing tool 110, heat is transferred from the heated metal block to the surface refinishing tool 110. An advantage of the metal block as the heating device 120 is that since the heating device 120 is external to the surface refinishing tool 110, melting of the surface to be treated can be stopped almost instantaneously by simply releasing the metal block from the surface refinishing tool 110. Thus, in this embodiment, cooling and reheating of the heating device 120 between each cycle is not necessary, since the metal block can be maintained at a constant temperature. This leads to reduced cycle times, resulting in faster turnaround times. In this embodiment, copper is used to make the metal block. In an alternative embodiment, the metal block comprises a metallic material including one or more of iron, steel, copper, and aluminum. In an alternative embodiment, the heating device 120 can be internal to and integrated with the surface refinishing tool 110.

[0042] In this embodiment, the heating device 120 is moved relative to the surface refinishing tool 110 by operating another actuator 140. As shown in FIG. 1 , the actuator 140 includes a cylinder 142 including a piston 144 connected to a piston rod 146. In this embodiment, the cylinder 142 is a pneumatic cylinder operable to linearly move the heating device 120 by linearly moving a second piston 144 within the second cylinder 142. A bracket on an upper end of the actuator 140 is connected to the heating device 120.

[0043] Actuator 130 and actuator 140 are not limited to being pneumatic cylinders, but in other embodiments may be hydraulic cylinders, electric actuators, or the like.

[0044] The device 100 also includes a cooling device operable to cool the surface refinishing tool 110, thereby resolidifying the molten layer created on the treated surface. The cooling device includes a cooling fluid source (e.g., containing air, water, oil, etc.) connected to the surface refinishing tool 110. In one embodiment of the invention, the cooling device is operable to flow a cooling fluid through one or more internal fluid channels 113 of the surface refinishing tool 110.

[0045] In another embodiment of the invention, the device 100 further includes a plurality of sensors (shown in FIG. 2B and FIG. 4) configured to measure at least one process control parameter of the surface treatment method being performed in the device 100. The process control parameters include, for example, the temperature of the surface refinishing tool 110 and / or the heating device 120, the pressure exerted by the surface refinishing tool 110 on the surface to be treated, the position of the surface refinishing tool 110 relative to the surface to be treated, the position of the heating device 120 relative to the surface refinishing tool 110, and the thickness of the melt layer on the surface. The plurality of sensors includes one or more of a position sensor, a temperature sensor, a pressure sensor, a depth sensor, and a solidification sensor. The position sensor may be, for example, an inductive sensor or a light-based sensor. The solidification sensor may be, for example, a fiber optic refractive index sensor. Several different types of sensors are known and readily available, and thus, one of ordinary skill in the art may use any suitable sensor.

[0046] In an alternative embodiment of the invention, the device 100 further includes a control unit configured to control the surface treatment method based on one or more measurements obtained by one or more of the multiple sensors. In one example, the control unit may be configured to control the dissolution of the surface to be treated, whereby when the measurements obtained by the depth sensor indicate that a maximum thickness of the dissolved layer has been reached, the control unit sends a signal to deactivate the heating device 120 and to stop further heating of the surface refinishing tool 110 to stop dissolution of said surface. In another example, the control unit may send a signal to activate the heating device 120 when the surface refinishing tool 110 is below the melting temperature of the material of the 3D printed part.

[0047] FIG. 1 further shows an insulating device 121 coupled to the heated metal block 120. The insulating device 121 is configured to prevent the loss of heat from the heated metal block 120 so that the heated metal block 120 can be efficiently maintained at a desired temperature. The insulating device 121 also protects other parts of the device 100 that do not require heating. For example, the insulating device 121 is used to help prevent the piston rod 136 from heating, so that the piston rod 136 does not transfer significant thermal energy from the heated metal block 120 to the resurfacing tool 110. In addition, because the tolerances of the components in the device 100 are fairly small, the insulating device 121 also helps to avoid changes in temperature that could otherwise induce thermal expansion that could later affect the friction between the sliding surfaces.

[0048] The device 100 further includes a number of inlet / outlet ports 150. The first port 150 is used to connect the device 100 to a cooling fluid source for supplying refrigerant to the surface refinishing tool 110 for cooling the surface refinishing tool 110. The second port 150 is used to connect the device 100 to a pressurized fluid source for powering the actuators 130 and 140.

[0049] 2A shows a perspective view of the surface refinishing tool 110 of the device 100 of FIG. 1. In this embodiment, the surface refinishing tool 110 includes a plurality of openings / vents 111 and 112. In this embodiment, the opening / vent 111 is located in an outer region of the surface refinishing tool 110 and the opening / vent 112 is located in a central region of the surface refinishing tool 110. The plurality of openings / vents 111 and 112 allow cooling fluid to enter and exit the surface refinishing tool 110 while cooling the surface refinishing tool 110. In an alternative embodiment, the plurality of openings / vents 111 and 112 may be located differently depending on the contour of the surface to be treated.

[0050] FIG. 2A also shows an elongated neck portion 117 for connecting the surface refinishing tool 110 to the piston rod 136 so that the surface refinishing tool 110 can be moved linearly relative to the 3D printed part being processed.

[0051] 2B shows a cross-sectional view of the surface refinishing tool 110 of the device 100 of FIG. 1. In this embodiment, multiple openings / vents 111 and 112 open into one or more internal fluid channels 113 in the surface refinishing tool 110. In this embodiment, the internal fluid channels 113 are interconnected via ducts 114 and 115. The internal fluid channels 113 allow a coolant to circulate within the surface refinishing tool 110 to cool the surface refinishing tool 110.

[0052] FIG. 2B also shows the opening / vent 111 in cross-section. As shown, the opening / vent 111 is located in an exterior region of the surface refinishing tool 110. The positioning of the opening / vent 111 on the surface refinishing tool 110 allows for a cooling fluid to be rapidly circulated around the periphery of the surface refinishing tool 110 via one or more interior fluid channels 113 to form a cooling barrier for the melt layer on the surface being treated. An advantage of the cooling barrier is that it prevents the melt pool from spilling over the exterior edge 119 of the surface refinishing tool 110, as it helps to rapidly solidify the melt layer around the exterior edge 119 to form a seal. Another advantage of providing a cooling barrier is that maintenance costs are reduced since an exterior sealing ring is not required and therefore replacement of the exterior sealing ring is not required. Yet a further advantage is that the contact pressure does not have to be very high due to the self-forming seal of the material (e.g., plastic). Similarly, openings / vents 112 are located in a central region of the resurfacing tool 110 to provide a cooling barrier around the inner edge of the molten layer.

[0053] 2B also shows internal threads 118 on the inner surface of elongated neck 117. Internal threads 118 are configured to engage complementary threads provided on piston rod 136 to connect resurfacing tool 110 to piston 132. In alternative embodiments, various fittings, such as push fittings, welds, barbed fittings, threaded fittings, flange fittings, or suitable adapters, may be used to attach resurfacing tool 110 to piston rod 136. Several such fittings are well known and may be readily used by one of ordinary skill in the art.

[0054] 2B also shows a cavity 190 for housing a temperature sensor within the surface refinishing tool 110. The temperature sensor is configured to measure the temperature of the surface refinishing tool 110 and may be installed within the cavity 190 using a heat transfer paste to ensure that a rapid temperature reading is possible. In one embodiment of the present invention, the temperature measurement is communicated to a control unit, which then sends a signal to actuate the piston 132 to position the surface refinishing tool 110 according to the surface treatment method being performed within the device 100.

[0055] FIG. 2B also shows the contact surface 116 of the surface refinishing tool 110. As mentioned above, the contact surface 116 includes the negative shape of the surface to be treated. The surface refinishing tool 110 is machined to the exact dimensions of the surface to be treated, and the contact surface 116 is treated to have a high surface finish. A high surface finish of the contact surface 116 is necessary because the surface finish of the contact surface 116 is transferred to the surface to be treated when the surface refinishing tool 110 is pressed against the surface to be treated. Thus, the surface finish of the contact surface 116 has a direct effect on the overall surface finish of the treated surface. Thus, the selection of the material of the surface refinishing tool 110 is an important factor in achieving the desired surface finish on the surface to be treated, since the material used affects the smoothness of the surface refinishing tool 110. In one or more embodiments of the present invention, the average surface roughness Ra value of at least a portion of the contact surface 116 of the surface refinishing tool is preferably less than about 2 to about 2.4 μm. For example, the average Ra value may be less than 1 μm, such as in the range of about 0.7 to 0.9 μm.

[0056] In this embodiment of the invention, the refinishing tool 110 is made of a copper material. Using a metallic material is advantageous because metals are generally good conductors of heat and electric current. Also, because metals are malleable and ductile, it is possible to machine them to precise surface dimensions. For similar reasons, it is also possible to create high gloss surfaces on metal parts. These characteristics of metallic materials are therefore advantageous for making the refinishing tool 110. In alternative embodiments of the invention, other materials may be used, for example, one or more of iron, aluminum and steel, or copper-containing alloys. In another embodiment, the refinishing tool 110 may additionally be coated to obtain an inert surface that does not adversely affect the material of the 3D printed part.

[0057] FIG. 3 shows a perspective view of the device 100 of FIG. 1. In this embodiment, the device 100 includes a fastening device 160 located near the top of the device 100. The fastening device 160 is operable to secure a 3D printed part to the device 100 during the surface treatment method. In this embodiment, the fastening device 160 is a flange-type lever lock including a fixed flange portion 162 connected to a movable flange portion 164. The flange portions 162 and 164 are operable to open and close the fastening device 160 as needed via handles attached to said flange portions. FIG. 3 shows the fastening device 160 when open and ready to receive a 3D printed part in the device 100 for surface treatment. In other embodiments of the invention, various types of fastening devices 160 may be used, for example clamps. Additionally, the fastening device 160 may be configured for manual or automatic operation.

[0058] 3 also shows a position sensor 192 for measuring a position of the piston 134 in the cylinder 132. Since the surface refinishing tool 110 is connected to the piston 134, the measurement obtained by the position sensor 192 can be correlated to a position of the surface refinishing tool 110 relative to the surface to be treated. In one embodiment of the present invention, the control unit can be configured to control the surface treatment method by controlling the movement of the piston 134 in the cylinder 132. For example, the control unit can be configured to turn on a red indicator light on the position sensor 192 when a first measurement obtained by the position sensor 192 correlates to a first position of the surface refinishing tool 110 where the surface refinishing tool 110 is pressed against the surface to be treated and dissolution begins.

[0059] In another example, the control unit can be configured to turn on a green indicator light on the position sensor 192 when a second measurement result obtained by the position sensor 192 correlates with a second position of the surface refinishing tool 110 where the surface refinishing tool 110 is stored and thus the surface refinishing tool 110 can safely be removed from the device 100.

[0060] In this embodiment, the position sensor 192 is an inductive sensor, although other types of position sensors, for example light-based sensors, could readily be used by one skilled in the art.

[0061] 3 also shows a plurality of fluid control valves 152 attached to the plurality of inlet / outlet ports 150. The first fluid control valve 152 is configured to control the flow of cooling fluid to one or more internal fluid channels 113 of the surface refinishing tool 110 to cool the surface refinishing tool 110. The second fluid control valve 152 is configured to control the flow of pressurized fluid to actuate the pistons 134 and 144.

[0062] Figure 3 also shows a safety cover 180 for covering any moving parts of device 100 to ensure safety during use. Also shown in Figure 3 is a base 170 for facilitating mounting device 100 to a work bench using any suitable fastening device, such as screws. Additionally shown is a connector 154 mounted near the base of device 100. In one embodiment of the invention, connector 154 is used to connect device 100 to a control unit to control a heat treatment method implemented within device 100.

[0063] In another embodiment of the invention, the device according to the invention comprises a vacuum unit to minimize the risk that trapped air bubbles will damage the surface to be treated during dissolution.

[0064] FIG. 4 shows a cross-sectional view of a device 200 according to a second embodiment of the present invention. The device 200 includes a surface refinishing tool 210, a heating device 220, and a locking device 295. In this embodiment, the heating device 220 is integral with the surface refinishing tool 210. In one example, the heating device 220 is an induction coil powered by an electric current. The advantage of this configuration is that the device 200 is more compact and lighter compared to the device 100, since the metal block and the actuator that moves the metal block are eliminated. This configuration is particularly useful when the surface to be treated has a smaller surface area, since the surface refinishing tool 210 is also smaller. Therefore, the time taken to heat and cool the smaller surface refinishing tool 210 is significantly shorter, and therefore repeated heating and cooling does not make a big difference in the cycle time and therefore in the total build time.

[0065] The actuator 230 is operable to move the surface refinishing tool 210 to releasably press against the treated surface of the 3D printed part. As shown in Figure 4, the actuator 230 includes a cylinder 232 including a piston 234 connected to a piston rod 236. In this embodiment, the cylinder 232 is equipped with a locking device 295 operable to lock the piston 234 in place to provide additional control over the surface treatment method.

[0066] 5 shows a flow chart illustrating a method 400 for surface treatment of a 3D printed part according to a third embodiment of the present invention. The method 400 is generally applicable to 3D printed parts that include thermoplastic materials. Thus, only the process parameters will differ based on the particular thermoplastic polymer from which the 3D printed part is made.

[0067] Method 400 can be used to provide localized treatment in a portion of a 3D printed part without creating a sharp boundary line where the resurfacing tool terminates. To accomplish this, the outermost edge of the heated tool can be cooled (e.g., either actively or passively to provide a non-linear temperature profile or step). Thus, when the molten material is in contact with the heated tool, it then flows into the central contact area and subsequently solidifies when it reaches the cooled or relatively cool edge of the resurfacing tool. This also allows the resurfacing tool to provide a self-sealing action without requiring the use of extreme pressures that are typically required for reshaping methods such as injection and some other types of casting.

[0068] As shown, method 400 includes a heating step 402 , a pressing step 404 , a stopping step 406 , a cooling step 408 , and a releasing step 410 .

[0069] The heating step 402 involves heating a resurfacing tool (which may also be referred to as a smoothing tool) to a temperature above the melting temperature of the material of the 3D printed part prepared for surface treatment. This is accomplished by activating a heating device connected to the resurfacing tool. In one embodiment of the invention, the heating step 402 involves activating the heating device by linearly moving the heating device to press against the resurfacing tool. In another embodiment, the heating step 402 involves activating the heating device by switching on a heating element embedded in the resurfacing tool.

[0070] The temperature to which the resurfacing tool is heated depends on the material of the 3D printed part being processed. Thus, for example, if the material is polypropylene (PP), the resurfacing tool may be heated to a temperature in the range of about 160°C to 166°C.

[0071] In another example, if the material is PP adapted for 3D printing, for example PP mixed with PE, which has a melting temperature of about 125°C, the resurfacing tool can be heated to about 240°C. This is done to quickly melt the outermost surface to a very low viscous state for the plastic to flow easily. The outermost surface is then quickly cooled so that as much of the 3D printed part as possible remains unaffected by the heat to avoid deformation and shrinkage.

[0072] The pressing step 404 includes pressing a surface refinishing tool against the treated surface of the 3D printed part to melt the treated surface and form a melted layer of material on the surface. This is accomplished by operating an actuator connected to the surface refinishing tool to move the surface refinishing tool to a first position relative to the treated surface. As the material of the 3D printed part melts at the surface, the melted material, due to its low viscosity, flows over the surface to fill gaps and voids therein, thus leveling them.

[0073] The stopping step 406 includes stopping the heating of the surface refinishing tool to stop the melting of the material. This is accomplished by deactivating a heating device connected to the surface refinishing tool. In one embodiment of the invention, the stopping step 406 is performed such that the thickness of the melted layer formed at the surface is relatively shallow, such that the body of the 3D printed part is hardly affected by the heat treatment. For example, the final solidified cooling layer formed may be to a depth of about 5, 10, 15, 20, 30, 40 or 50 μm, etc., within the processed 3D printed part. In one embodiment of the invention, the heating device is deactivated by linearly moving the heating device to release it from the surface refinishing tool. In another embodiment, the heating device is deactivated by switching off a heating element integral with the surface refinishing tool.

[0074] A cooling step 408 includes cooling the surface refinishing tool to resolidify the melted layer formed on the surface to create a treated surface. Cooling is accomplished by connecting a source of cooling fluid to the surface refinishing tool. In one embodiment of the invention, the cooling fluid is flowed through one or more internal fluid channels in the surface refinishing tool. This prevents the melted material from spilling out of the treatment area, as it solidifies when it reaches the cooling barrier at the edge. This creates a seal, which is advantageous as it eliminates the use of specially designed edge seals that would leave marks on the finished details.

[0075] A releasing step 410 includes releasing the surface refinishing tool from the treated surface, which is accomplished by operating a piston connected to the surface refinishing tool to move the surface refinishing tool to a second position relative to the treated surface.

[0076] The following experiments were conducted to compare the improvement in surface finish between an untreated surface and a surface treated using the method and apparatus of the present invention. The following experiments were also conducted to compare the surface finish obtained by using the method and apparatus of the present invention with known tumbling methods.

[0077] Experiment 1 A first type of 3D printed polypropylene connector was used for this experiment as Sample 1. Sample 1 was subjected to the surface treatment method 400 of the present invention on its top and bottom surfaces to improve the surface finish of said surfaces. Before and after subjecting Sample 1 to the surface treatment process 400, the surface roughness of Sample 1 was measured as Ra values ​​on both the top and bottom surfaces using a confocal microscope. The measured Ra values ​​are provided in Table 1 below in μm. The Ra values ​​were measured at four different locations on the top surface and averaged to obtain an average Ra value for the top surface. Similarly, the Ra values ​​were measured at four different locations on the bottom surface and averaged to obtain an average Ra value for the bottom surface.

[0078] [Table 1]

[0079] A comparison of the Ra values ​​measured before and after the surface treatment process shows a significant decrease in the Ra value as a result of the surface treatment. As seen in Table 1, for the top surface of Sample 1, the average / mean Ra value before treatment was 15.97, which decreased to an average Ra value of 1.714 after surface treatment, representing an 89.27 percent reduction in the mean Ra value after surface treatment. Similarly, for the bottom surface, the average Ra value before treatment was 20.47, which decreased to an average Ra value of 1.0835 after surface treatment, representing a 94.71 percent reduction in the mean Ra value after surface treatment.

[0080] Experiment 2 Two identical second type 3D printed polypropylene connectors were used for this experiment as sample 2. In this embodiment, the first sample 2 was subjected to a known tumbling post-treatment process, and the second sample 2 was subjected to the surface treatment method 400 of the present invention. The Ra value of the first sample 2 was measured after the first sample 2 was subjected to the tumbling process on the first and second sides of the first sample 2. Similarly, the Ra value of the second sample 2 was measured after the second sample 2 was subjected to the surface treatment process of the present invention on the first and second sides of the second sample 2. The Ra values ​​measured by confocal microscopy for the first and second sample 2 are provided below in Table 2. The Ra values ​​for the first sample 2 were measured at four different locations on each of its first and second sides and averaged to obtain an average Ra value corresponding to the first and second sides of the first sample 2. Similarly, the Ra values ​​were measured and averaged for the second sample 2.

[0081] [Table 2]

[0082] A comparison of the Ra values ​​measured for the second sample 2 shows a much lower value compared to the Ra values ​​measured for the first sample 2, indicating that the surface treatment method 400 of the present invention provides a better surface finish compared to known tumbling processes.

[0083] As shown by the above experiments, the method 400 of the present invention was able to result in average surface roughness Ra values ​​down to the range of 0.773 to 1.714 on the treated surface.

[0084] With conventional tumbling, it is generally possible to obtain an average processed surface Ra value of about 4 μm. However, obtaining such a value for any internal surface of a 3D printed part is difficult as the internal surfaces are not easily accessible, and therefore the surface finish varies near the internal surfaces and near any external edges / corners. Narrow channels in such parts are also difficult to process using this type of post-processing technique.

[0085] Thus, a tumbled 3D printed part, such as a 3D printed part for a bioprocessing device having a valve seat formed within its internal channel, may ultimately not even achieve an average Ra value of 4 μm in some system-critical areas, e.g., Ra values ​​approaching the untumbled / raw Ra value of Experiment 1 above (e.g., greater than the average value of about 16 μm) may still be present in the internal valve seat area.

[0086] The Ra value can be determined by using a confocal laser microscope to image a small portion of the surface. Taking a line section across the image provides an Ra profile for this particular section of the surface in a particular direction. Various other techniques for characterizing the surface, such as based on measuring roughness parameters, can also be used as desired.

[0087] Other techniques (e.g., non-optical, contact type) can also be used to measure Ra, for example by using a very delicate needle that is dragged over a specified length of the surface. However, these techniques can be undesirable when working with 3D printed plastic materials, as they can effectively scribe lines into the plastic, thus resulting in an Ra measurement that appears smoother than it actually is.

[0088] Figure 6 shows a top view of an untreated surface and a top view of a surface treated according to the surface treatment method of the present invention at a magnification of 290x. Image c) shows an untreated surface with a granular surface topology, with visible pores and cracks. Image b) shows a surface that has been subjected to the surface treatment method of the present invention, where the surface topology appears non-granular and smooth, since the pores and cracks are filled by melting and resolidifying the surface.

[0089] FIG. 7 shows scanning electron microscope (SEM) images of cross-sections of small heat treated samples with magnifications a) 200x BSD, b) 230x BSD, c) 280x BSD, d) 850x BSD, e) 2250x BSD. Samples of treated surfaces according to the method of the invention were freeze-fractured and studied using SEM imaging. Freeze-fracturing was used to avoid the use of tooling that would otherwise make the affected layer appear thicker than it actually is. As shown in FIG. 7, the dissolution at the surface is highly localized, about 10 μm thick or so. Thus, the remainder of the material is not affected by the surface treatment method of the invention.

[0090] Various aspects and embodiments of the present invention have been described herein. However, it will be readily apparent to one skilled in the art that the present invention should not be considered limited to the above-described embodiments, but may vary within the scope of the appended claims.

[0091] The bioprocessing equipment may be, for example, but not limited to, a chromatography system, a filtration system, an aseptic filling system, a fermentation system, a bioreactor assembly, or a mixer assembly. In one or more embodiments of the present invention, the device may be operated manually, semi-automatically, or fully automatically. The source of cooling fluid may be, for example, a source of cooling air or gas, or a cooling fluid. The device of the present invention may be used as a stand-alone device or may be part of an assembly line. In one or more embodiments of the present invention, the method for surface treatment may be performed manually, semi-automatically, or fully automatically. The method of the present invention may be performed using a PLC-based control unit by using one or more closed feedback loops to control various process parameters. The method of the present invention may also be performed using an open-loop configuration. The device of the present invention may be used to process a variety of 3D printed parts by adapting the surface refinishing tool to the shape of the surface to be treated. The control unit may be a computing device, a semiconductor-based microprocessor, a central processing unit (CPU), an application specific integrated circuit (ASIC), and / or other hardware processing device. The controller may be a separate component or may be integrated with the device. [Explanation of symbols]

[0092] 100 devices 110 Surface Refinishing Tools 111 Openings / Ventilation 112 Openings / Ventilation 113 Internal Fluid Channel 114 Duct 115 Duct 116 Contact surface 117 Long and thin neck 118 Female thread 119 Outer Edge 120 Heating Device 121 Isolation Devices 130 Actuator 132 Piston 134 Piston 136 Piston rod 140 Actuator 142 cylinders 144 Second Piston 146 Piston rod 150 inlet / outlet ports 152 Fluid Control Valve 154 Connector 160 Fixed Devices 162 Fixed flange part 164 Movable flange section 170 base 180 Safety Cover 190 Sensor, Cavity 192 Sensors 200 devices 210 Surface Refinishing Tools 220 Heating Devices 230 Actuator 232 Cylinder 234 Piston 236 Piston rod 292 Sensors 295 Lock Device

Claims

1. A device (100, 200) for the surface treatment of 3D printed parts for a bioprocessing device, comprising: a surface refinishing tool (110, 210) including a contact surface (116) that includes a negative shape of a surface to be treated of the 3D printed part; a heating device (120, 220) operable to heat the surface refinishing tool (110, 210) to a temperature above a melting temperature of a material of the 3D printed part; an actuator (130, 230) operable to move the surface refinishing tool (110, 210) such that the actuator (130, 230) can releasably press the surface refinishing tool (110, 210) against the surface to be treated to dissolve the surface to form a dissolved layer of material on the surface to be treated; a cooling device operable to cool the surface refinishing tool (110, 210) and thereby resolidify the dissolved layer of material at the treated surface to form a treated surface; A device (100, 200) comprising:

2. The heating device (120, 220) an externally heated metal block (120) configured to be releasably pressed against said refinishing tool (110); or a heating element (220) integral with said resurfacing tool (210); The device (100, 200) of claim 1, comprising:

3. The device (100, 200) of claim 1 or claim 2, wherein the actuator (130, 230) is operable to move the surface refinishing tool (110, 210) in a substantially linear manner.

4. 4. The device (100, 200) of claim 1, wherein the actuator (130, 230) comprises a cylinder (132, 232) including a piston (134, 234), the piston (134, 234) being connected to the surface refinishing tool (110, 210).

5. The device (200) of claim 4, further comprising a locking device (295) operable to lock the piston (234) in place within the cylinder (232).

6. a plurality of sensors (190, 192, 292) configured to measure at least one process parameter of a surface treatment method (400) being performed in said device (100, 200); a control unit configured to control the surface treatment method (400) based on one or more measurements obtained by one or more of the plurality of sensors (190, 192, 292); The device (100, 200) of any one of claims 1 to 5, further comprising:

7. The device (100, 200) of claim 6, wherein the plurality of sensors (190, 192, 292) includes one or more of a position sensor (192, 292), a temperature sensor (190), a pressure sensor, a depth sensor, and a coagulation sensor.

8. The device (100, 200) of any one of claims 1 to 7, wherein the cooling device comprises a cooling fluid source connected to the surface refinishing tool (110, 210).

9. The device (100, 200) of any one of claims 1 to 8, wherein the surface refinishing tool (110, 210) comprises one or more internal fluid channels (113).

10. The device (100, 200) of any one of claims 1 to 9, wherein the material of the surface refinishing tool (110, 210) comprises a metallic material including one or more of copper, iron, steel, and aluminum.

11. At least a portion of the contact surface (116) of the resurfacing tool (110, 210) has a thickness of less than about 16 μm, less than about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2.4, 2, 1.6, 1.5 or 1 μm, from about 0.5 μm, from about 0.4, 0.5 or 0.6 μm to about 0.7, 0.8 or 0.9 μm, from about 0.7 to about 0.8 or 0.9 μm 11. The device (100, 200) according to claim 1, having a low average surface roughness value Ra (μm) ranging from about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9 μm to about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2.4, 2, 1.6, 1.5 or 1 μm.

12. The device (100, 200) of any one of claims 1 to 11, further comprising a fixing device (160) operable to fix the 3D printed part to the device (100, 200) during the surface treatment process (400).

13. 13. The device (100, 200) of any one of claims 1 to 12, wherein the surface refinishing tool (110, 210) is configured to engage a valve seat portion of the 3D printed part.

14. 1. A method (400) for surface treatment of 3D printed parts for a bioprocessing device, comprising: Heating (402) a surface refinishing tool to a temperature above a melting temperature of a material of the 3D printed part prepared for surface treatment; pressing (404) the surface refinishing tool against a target surface of the 3D printed part to melt the target surface and form a melted layer of the material on the target surface; ceasing (402) the heating of the refinishing tool to stop the dissolving (406); cooling (408) the surface refinishing tool to resolidify the dissolved layer formed on the treated surface to create a treated surface; Releasing the refinishing tool from the treated surface (410); The method (400).

15. 15. The method (400) of claim 14, wherein the thickness of the dissolved layer at the surface is in the range of less than about 10, 15, 20, 30, 40 or 50 μm, in the range of 0.1 to 10.0 μm, in the range of about 4.0 to 9.0 μm, and / or in the range of about 6.0 to 8.0 μm.

16. 16. The method (400) of claim 14 or claim 15, wherein the heating step (402) comprises heating the resurfacing tool to a temperature at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% above a melting point temperature (MP) of the material of the 3D printed part, or from about 10%, 20%, 30%, 40%, 50% to about 70%, 80%, 90%, or from 100% to about 150%, for example to about 240°C if the material is PP mixed with PE which has a melting temperature of about 125°C.

17. 17. The method (400) of any one of claims 14 to 16, wherein the heating (402) and deactivating (406) steps comprise activating and deactivating, respectively, a heating device connected to the surface refinishing tool.

18. 18. The method (400) of any one of claims 14 to 17, wherein the cooling step (408) comprises flowing a cooling fluid through one or more internal fluid channels of the surface refinishing tool.

19. 19. The method (400) of any one of claims 14 to 18, wherein the pressing (404) and releasing (410) steps comprise actuating a piston in a cylinder to move the surface refinishing tool to a first position and a second position, respectively, relative to the surface to be treated.

20. 20. The method (400) of any one of claims 14 to 19, wherein the pressing (404) comprises placing a contact surface of the surface refinishing tool in contact with the surface to be treated.

21. 3D printed parts for bioprocessing equipment, comprising: less than about 16 μm, less than about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2.4, 2, 1.6, 1.5 or 1 μm, about 0.5 μm, about 0.4, 0.5 or 0.6 μm to about 0.7, 0.8 or 0.9 μm, about 0.7 to about 0.8 or 0.9 μm, and and / or the 3D printed part includes at least a partial surface portion thereof having an average surface roughness value Ra (μm) in the range of about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9 μm to about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2.4, 2, 1.6, 1.5 or 1 μm.

22. 22. The 3D printed part of claim 21 , wherein the at least partial surface portion comprises a valve seat, an interior surface, and / or a connector / adapter interface.

23. 23. The 3D printed part of claim 21 or claim 22, wherein the part material comprises one or more of a thermoplastic material, polypropylene (PP), polyurethane (PE), and / or a cyclic olefin copolymer (COC) polymer.

24. 24. The 3D printed part of any one of claims 21 to 23, comprising a surface treated layer having a depth in the range of less than about 10, 15, 20, 30, 40, or 50 μm, in the range of about 0.1 to 10.0 μm, in the range of about 4.0 to 9.0 μm, and / or in the range of about 6.0 to 8.0 μm.

Images