Patent Publication Number: US-2017368745-A1

Title: 3d printing process augmentation by applied energy

Description:
PRIORITY CLAIM 
     The application claims priority to U.S. Provisional Patent Application Ser. No. 62/355,183 filed Jun. 27, 2016; the disclosure of which is incorporated herewith by reference. 
    
    
     BACKGROUND 
     The present disclosure is directed to additive manufacturing techniques for printing three-dimensional (3D) parts. In additive manufacturing processes, layers of material are deposited and bonded together (optionally onto an object or a substrate) according to a prescribe pattern or design to create a 3D object. A 3D printer implements this printing process by depositing layers of material in the form of a liquid, a powder, an extrusion (e.g. a wire) or a sheet so that each layer of material fuses to previously deposited modeling material. The part material is deposited via a print head incrementally along the x-y plane and then along a z-axis (perpendicular to the x-y plane) to form a 3D part. 
     Movement of the print head with respect to the substrate is performed under computer control, in accordance with build data that represents the 3D part. The build data is obtained by initially slicing a digital representation of the 3D part into multiple horizontally sliced layers. Then, for each sliced layer, the host computer generates a tool path for depositing the part material to print the 3D part. 
     In fabricating 3D parts by depositing of layers of part material, support layers or structures are typically built underneath overhanging portions or in cavities of objects under construction, which are not supported by the part material itself. A support structure may be built utilizing the same deposition techniques by which the part material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D part being formed. Support material is then deposited from a second print head pursuant to the generated geometry during the build process. The support material adheres to the part material during fabrication and is removable from the completed 3D part when the build process is complete. 
     Existing 3D printing processes, such as fused deposition modeling (FDM) have several drawbacks. For example, most forms of 3D printing using thermoplastics have inherent porosity and surface roughness, leading to concerns in the medical field regarding bioburden. 
     SUMMARY 
     The present disclosure is directed to a method for three-dimensional printing comprising printing a three-dimensional part formed from a first material, the first material including energy sensitive particles and applying energy to the three-dimensional part during or after printing to heat the energy sensitive particles and melt the first material, allowing reflow thereof. 
     In an embodiment, the energy sensitive particles are one of magnetic induction or microwave radiation sensitive particles. 
     In an embodiment, the method may further comprise printing a support structure configured to restrain the three-dimensional part in a first configuration, the support structure formed from a second material. 
     In an embodiment, the method may further comprise removing the support structure from the three-dimensional part so that the three-dimensional part deforms to a second configuration. 
     In an embodiment, the second material includes energy sensitive particles 
     In an embodiment, the method further comprises applying energy to the support structure during or after printing to heat the energy sensitive particles and melt the second material away from the three-dimensional part. 
     In an embodiment, the energy sensitive particles are formed of a biocompatible material. 
     In an embodiment, the first material is a thermoplastic. 
     In an embodiment, the three-dimensional part is printed using a layer-based additive manufacturing technique. 
     The present disclosure is also directed to a method for three-dimensional printing comprising printing a three-dimensional part formed from a first material, printing a support structure formed from a second material, the second material including energy sensitive particles, wherein the support structure is attached to the three-dimensional part, and applying energy to the support structure during or after printing to heat the energy sensitive particles and melt the second material, wherein melting of the second material detaches the support structure from the three-dimensional part. 
     In an embodiment, the energy sensitive particles are formed of a biocompatible metal. 
     In an embodiment, the three-dimensional part is printed using a layer-based additive manufacturing technique. 
     In an embodiment, the first and second materials are thermoplastics. 
     The present disclosure is also directed to an object printed with a three-dimensional printing system, the object comprising a support structure formed of a first material, and a three-dimensional part coupled to the support structure, the part being formed from a second material including energy sensitive particles, wherein application of energy to the three-dimensional part causes the energy sensitive particles to melt the second material, allowing reflow thereof. 
    
    
     
       BRIEF DESCRIPTION 
         FIG. 1  shows a side view of a system according to a first exemplary embodiment of the disclosure; 
         FIG. 2  shows a side view of a 3D part and support structure of the system of  FIG. 1 ; 
         FIG. 3  shows another side view of the system of  FIG. 1  during application of magnetic induction or microwave radiation; 
         FIG. 4  shows another side view of the system of  FIG. 1  during application of magnetic induction or microwave radiation; 
         FIG. 5  shows another side view of the system of  FIG. 1  using multiple deformable 3D parts; 
         FIG. 6  shows another side view demonstrating the energy application process to the 3D parts of  FIG. 5 ; 
         FIG. 7  shows another side view of the system of  FIG. 1  demonstrating the printing process of 3D part and support structure; 
         FIG. 8  shows another side view demonstrating the energy application process of 3D part and support structure of  FIG. 7 ; 
         FIG. 9  shows a side view of the 3D part and support structure of  FIGS. 7-8  demonstrating the removal of the support structure from the 3D part; 
         FIG. 10  shows another side view of the system of  FIG. 1  demonstrating the energy application process of 3D part and support structure according to another exemplary embodiment of the present disclosure; and 
         FIG. 11  shows a side view of another exemplary 3D part and support structure of the system of  FIG. 1  demonstrating the removal of the support structure from the 3D part. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present disclosure is directed to a process for printing a 3D part and/or a support structure. Exemplary embodiments of the present disclosure describe a process for printing a 3D part/support structure using a material that includes the addition of energy sensitive materials. The process also involves an energy application cycle using microwave/induction energy, in which the 3D part and/or support structure are heated to melt one or both of the parts. 
     The present disclosure is directed to the incorporation into 3D print materials of energy sensitive materials, such as materials that absorb microwave energy or magnetic or electric energy through induction. These energy sensitive materials may be incorporated into all or part of a printed 3D object (e.g., in particulate form) to impart properties to the materials that can be used to achieve structural qualities as described in more detail below. In particular, a 3D object may be printed with a single material including energy sensitive particles or it may be printed with a combination of materials, some parts of the object including energy sensitive materials while others are without these materials. Application of energy, such as microwave radiation or magnetic induction energy, to material including these energy sensitive materials causes these materials to heat up or to enhance this heating up as compared to materials not including these energy sensitive materials. In the context of 3D printing, induced heating of materials including energy sensitive particles upon energy application during or after printing may be used to facilitate softening or melting of portions or all of the 3D part to, for example, make the object pliable so that its shape may be changed as desired, to smooth surfaces, or to facilitate the removal of structures included, for example, solely to support parts of the printed 3D object during the printing process. Energy can be applied at varying powers, frequencies, and exposure durations depending on the desired application and substance used. For example, more power and longer duration both result in more heat application. Frequency may also be tuned to be more or less effective for given materials and energy sensitive particle sizes. For example, a 3D object may include energy sensitive material distributed uniformly throughout the object. In this example, application of energy to the printed object heats the energy sensitive material to facilitate softening of the print material throughout the printed 3D object promoting redistribution/reflow of the material, reducing porosity of the entire object. This redistribution/reflow of the material of which the 3D printed object is formed may create a smoother surface of the 3D object. In another example, a 3D object may include energy sensitive material only in one or more portions of the 3D object. In this example, application of a first level of energy to the printed object may facilitate softening of these selected portions of the 3D object. However, upon application of a higher amount of energy, the parts of the 3D printed object including the energy sensitive particles may induce enhanced melting of the material to fill in spaces which the 3D printer was unable to print—i.e. difficult geometries or to secure together multiple separate parts intended to be fit securely together. In a further example, the 3D object may include a support structure printed from energy sensitive material. In this example, energy may be applied to melt away the support structure permitting its removal from the 3D object after printing has been completed. 
     As shown in  FIG. 1 , a system  100  according to a first exemplary embodiment of the present disclosure is an additive manufacture system for building 3D parts and support structures pursuant to the process of the present disclosure. In a preferred embodiment, the system  100  is a fused depositing modeling (FDM) system. However, any other additive manufacturing system may be used, as would be understood by those skilled in the art. The system  100  includes a print head  102  and an energy emitter  104  which emits energy such as, for example, magnetic induction or microwave radiation energy. As would be understood in the art, the energy emitter  104  may be housed within the 3D printer or may be separate from the 3D printer. The system  100  further includes a platform  106  for printing a 3D part  108  and, if necessary, a corresponding support structure  110 . 
     The 3D part  108  may be built on the platform  106 . The print head  102  prints the 3D part  108  on the platform  106  in a layer-by-layer manner, based on a preconceived design data provided from a controller (not shown). The print head  102  is configured to move in a horizontal x-y plane relative to the platform  106  based on signals provided from a controller (not shown). The x-y plane is a plane defined by an x-axis and a y-axis, where the x-axis and the y-axis are parallel to a vertical z-axis. In an embodiment, the platform  106  may move along the z-axis such that layers  138  of material may be printed on the platform  106 . In another embodiment, the platform  106  may move in the x-y plane while the print head  102  moves along the z-axis. Other similar configurations may also be used such that one or both of the platform  106  and the print head  102  are movable relative to one another. If a support structure  110  is necessary, the support structure  110  may also be built on the platform  106  in the same manner as the 3D part  108 . As described above, the print head  102  prints the support structure  110  on the platform  106  in a layer-by-layer manner, based on the preconceived design data provided from the controller (not shown). 
     In a preferred embodiment, the 3D part  108  and the support structure  110  may be printed from a single print head  102 . The print head  102  may, for example, have a single-tip extrusion head  114  configured to deposit both part material  116  and support structure material  118 . In another embodiment, the print head  102  may have a dual-tip extrusion head  114  with a first tip configured to deposit part material  116  and a second tip configured to separately deposit support material  118 . In a further embodiment, the system  100  may include a plurality of print heads  114  for depositing part material  116  and/or support material  118  from one or more tips. 
     The part material  116  and the support material  118  may be provided to the system  100  in a variety of different forms. In a preferred embodiment, the materials  116 ,  118  may be supplied to the print head  102  in the form of continuous filaments. For example, in the system  100 , the part and support materials  116 ,  118  may be provided as continuous filament strands fed to the print head  102 . In another embodiment, the material fed to the print head  102  may be a powder. In a further embodiment, the material may be granulated. 
     In an exemplary embodiment, the 3D part  108  is printed from a part material  116  that compositionally includes a polymer having energy sensitive materials  120  such as microwave or induction sensitive materials in a powder, granular or filament form. Examples of suitable part materials  116  include thermoplastic materials such as, for example, Acrylonitrile Butadiene Styrene (ABS), Acrylonitrile Styrene Acrylate (ASA), Nylon, Ultem and Polycarbonate. Energy sensitive materials  120  incorporated into the part material  116  may be formed of a biocompatible metal such as, for example, stainless steel, titanium, nickel and Nitinol. The energy sensitive materials  120  may also be any conductor with resistance. Energy sensitive materials may also be any molecule with a dipole moment as such molecules can be microwave heated. In an exemplary embodiment, the energy sensitive materials  120  are incorporated into the part material  116  homogeneously to allow for uniform behavior. In this embodiment, the support structure  110  may also be printed from a material similar to that of which the 3D part  108  is formed, such as, for example, thermoplastic materials. However, in this embodiment the support material  118  does not include energy sensitive materials  120 , as can be seen in  FIG. 2 . In another embodiment, the support material  118  also includes energy sensitive materials  120  incorporated therein and, in a further embodiment, the support material  118  may include energy sensitive materials  120  while the part material  116  does not. The energy sensitive materials  120  may also be formed of a biocompatible metal such as, for example, iron or copper. In this embodiment, the support material  118  may be the same as the 3D part material  116  or may include a different energy sensitive material  120  than the 3D part material  116 . In yet another embodiment, the support material  118  may include energy sensitive material  120  while 3D part material  116  does not include any energy sensitive material  120 . 
     The received part and support materials  116 ,  118  are deposited by the print head  102  onto the platform  106  to print the 3D part  108  in coordination with the printing of the support structure  110  using a layer-based additive manufacturing technique, as described above. As shown in  FIG. 2 , the 3D part  108  is printed as a series of successive layers  138  of the part material  116  and the support structure  110  is printed as a series of successive layers  140  of the support material  118  in coordination with the printing of the 3D part  108 . 
     The energy emitter  104  applies energy  122  such as microwave radiation or magnetic induction energy to the 3D part  108  and/or the support structure  110  to heat the energy sensitive particles  120  within the 3D part  108  and/or the support structure  110  until the material of either part reaches a transition temperature and softens or melts. The temperature required to melt a material may vary depending on the desired level of melt and the plastic being used. For example, the softening temperature (Tg) of ABS is 116° C. while full melt occurs at  224 ° C. In other examples, Nylon 12 Tg ranges from 41-170° C. with a melt temperature of between 130-200° C. (depending on grade) and Polycarbonate Tg occurs at 145-150° C. with full melt between 250-343° C. In a first embodiment, the energy  122  may be applied after the 3D part  108  and the support structure  110  have been printed. In a second embodiment, at least a portion of the energy application may be performed while the 3D part  108  and the support structure  110  are being printed, for example, by a heating mechanism within the print head  102 . As discussed below, this energy application enhances interlayer bonding, increases part strength and reduces porosity. 
       FIG. 2  shows an example of a simple 3D part  108  having a top surface  142 , lateral surfaces  144  and a bottom surface  146 . The support structure  110  is desirably deposited on two opposing lateral surfaces  144 . It will be understood that the system  100  may print 3D parts  108  having a variety of different geometries. The system  100  may also print corresponding support structures  110  that restrain, support, or encapsulate the 3D parts  108 , such as at the surfaces of the 3D parts  108 . Additionally, the support structures  110  may provide vertical support along the z-axis for any overhanging regions of the layers of the 3D parts  108 , allowing the 3D parts  108  to be built with a variety of geometries. 
       FIG. 3  illustrates a printed 3D part  108  undergoing modification through exposure to applied energy (e.g. microwave radiation or magnetic induction)  122 .  FIG. 3  shows the printed 3D part  108  in the process of undergoing reflow upon exposure to energy  122 . Referring to  FIG. 3 , the 3D part  108  is present upon platform  106  and was previously formed during the printing process and contains a lower layer  124  and an upper layer  126 . As can be seen, spaces  148  between strands in the layers make the 3D part  108  a porous build. Upon applying energy  122  from the energy emitter  104  across a portion of the 3D part  108 , melting and reflow of the lower layer  124  and the upper layer  126  can be achieved in a consolidated (i.e. denser) region  128 , providing greater structural integrity to the 3D part  108 . The remaining nonconsolidated portion  129  of the lower layer  124  and upper layer  126  can similarly be melted and reflowed as desired by applying energy  122  from energy emitter  104  to cause complete consolidation of the 3D part  108 . 
       FIG. 4  similarly shows how a printed 3D part  108 ′ can undergo surface smoothing upon exposure to energy  122  from the energy emitter  104 . As shown in  FIG. 4 , as-deposited, the 3D part  108 ′ initially has roughened surface  132  on outer layer  134  thereof. By applying energy  122  from the energy emitter  104  to the roughened surface  132 , energy sensitive particle  120  allow the material to reflow to form a smooth surface  136 . By continuing to apply energy  122  from the energy emitter  104  across 3D part  108 ′, extension of the smoothed surface  136  can be realized. 
     In some cases, 3D printed pieces and reflow may be part of secondary processes such as insert molding or blow molding. In such cases, thermoplastics used in printing of a 3D part  108  may be difficult to mold into specific geometries. In an exemplary embodiment, 3D part  108  may be printed in a form similar to the final desired form and placed in a ceramic mold. Energy emitter  104  is then focused on the 3D part so that the 3D part becomes more plastic and pressure is applied to allow the 3D part material to flow into the desired shape within the mold. In another exemplary embodiment, more complex geometries may be achieved by having the print head  102  print a majority of the 3D part material  116 , including energy sensitive particles  120 , where needed and then applying energy  122 . The energy emitter  104  may be focused on a specific location or the entire 3D part  108  to promote softening, melting and/or reflow of all or specific portions of the 3D part  108  to achieve geometries that could not be achieved by the print head  102  itself. 
     In another exemplary embodiment illustrated in  FIGS. 5-6 , a combination of model materials, energy sensitive and inert, may be used together to create multiple deformable 3D parts  108 . In this embodiment, the print head  102  may print multiple 3D parts  108  that may then be attached to one another or to other pieces freely in their undeformed states. In an alternate exemplary embodiment, a single 3D part may be printed and coupled to a non-printed part, such as an element formed using injection molding. The energy emitter  104  may then be focused on the multiple 3D parts  108  to melt the energy sensitive materials  120 , causing them to deform or melt into place, creating a secure fit between the multiple 3D parts  108 . 
       FIGS. 7-9  illustrate an exemplary method of the present disclosure for printing and energy application of the 3D part  108  including energy sensitive particles  120  and the support structure  110  without energy sensitive particles with the system  100 . While the method is described herein with reference to the 3D part  108  and the support structure  110 , the method may also be used for printing and energy application to 3D parts and support structures having a variety of geometries. As shown in  FIG. 7 , the 3D part  108  is printed in a series of layers  138  to define the geometry of the 3D part  108  having a vertical portion  150  and a lateral portion  152 . 
     The support structure  110  is also printed in a series of layers  140  in coordination with the printing of the layers  138  of the 3D part  108 , where the printed layers  140  of the support structure  110  are structured to apply tension to the vertical portion  150  to restrain the vertical portion  150  of the 3D part  108  in a specific geometry. For example, in  FIG. 7 , the restraining support structure  110  is printed at a free end of the vertical portion  150  to hold the vertical portion  150  in a desired position to facilitate printing. It is noted that in the present embodiment, the printed layers of the 3D part and the support structure  138 , 140  have substantially the same layer thickness. In an alternate embodiment, the layers  140  of the support structure  110  may differ in thickness from the 3D part layers  138 . As noted above, the support structure  110  may be printed at the same time as the 3D part  108  via the same print head  102  or a different print head  102 . In another embodiment, the support structure  110  may be printed after the 3D part  108  via the same print head  102  or a different print head  102 . 
     After the print operation has been completed, the 3D part  108  and the support structure  110  may then undergo an energy application cycle, as shown in  FIG. 8 . As discussed below, this cycle involves applying energy  122  to the parts  108 ,  110  to increase the temperature of the 3D part  108  and/or support structure  110  via the energy sensitive particles  120 . As shown in  FIG. 8 , the application of energy  122  causes the temperature of the energy sensitive particles  120  in the 3D part  108  to increase, causing the materials of the layers  138  to soften and/or melt and flow throughout or along the part  108  to eliminate surface roughness, spaces  148  and porosity within the layers, and to increase strength of the 3D part  108 . In this instance, the input of energy  122  to the 3D part  108  and the support structure  110  does not cause the support structure  110  to melt since parts lacking the energy sensitive particles  120  will not undergo effective heating. Thus, support structure  110  is shown with original printed layers  140  while 3D part layers  138  have been melted together. 
     After the energy application cycle has been completed, the resulting 3D part  108  and/or support structure  110  may be removed from the energy emitter  104  and the support structure  110  may be removed from the 3D part  108 , as shown in  FIG. 9 . For example, the support structure  110  may be removed by snapping or breaking it away from the 3D part  108 . In another example, the support material  118  may be partially soluble in water such that the resulting 3D part  108  and support structure  110  may be immersed in water to dissolve the support structure  110  for removal from the 3D part  108 . It is understood that the support structure  110  may be removed from the 3D part  108  by any other method known in art. The resulting 3D part  108  accordingly exhibits dimensions corresponding to the preconceived design. 
       FIGS. 10-11  illustrate another exemplary method of the present disclosure for printing and energy application of a 3D part with system  100 . As shown in  FIG. 10 , the 3D part  208  may be printed in the same manner as discussed above for 3D part  108  with layers  238  and including a vertical portion  250  and a lateral portion  252 . Similarly, the support structure  210  may be printed in the same manner as discussed above for the support structure  110  with layers  240 . However, in this example, the support structure  210  is composed of a material including energy sensitive particles  220  and the 3D part  208  is composed of a material without energy sensitive particles.  FIG. 10  shows 3D part  208  is printed in a first configuration with a geometry designed to solidify with sufficient internal tension to deform when released. After the print operation has been completed, the 3D part  208  and the support structure  210  undergo a similar energy application cycle, as illustrated in  FIG. 10 . In this embodiment, because it is the support structure  210  that includes energy sensitive particles  220 , the application of energy  222  causes the layers  240  of the support structure  210  to soften and/or melt. The support structure  210  consequently melts away from the 3D part  208  which does not undergo effective heating due to the lack of energy sensitive particles  220  therein. As can be seen in  FIG. 11 , because the support structure  210  no longer restrains the 3D part  208  in the printed configuration, the tension within the vertical portion  250  is released and the 3D part  208  is able to deform from the first configuration to a desired second configuration. 
     It will be apparent to those skilled in the art that various modifications may be made in the present disclosure, without departing from the scope of the disclosure. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided that they come within the scope of the appended claims and their equivalents.