Patent Publication Number: US-2021170680-A1

Title: Binder jetting apparatus and methods

Description:
PRIORITY INFORMATION 
     The present application claims priority to U.S. Provisional Patent Application Ser. No. 62/595,833 titled “Binder Jetting Apparatus and Methods” filed on Dec. 7, 2017, the disclosure of which is incorporated by reference herein. 
    
    
     FIELD 
     The present disclosure generally relates to methods and systems adapted to perform additive manufacturing (“AM”) processes, for example by binder jet printing. In particular, apparatus and methods are described for three-dimensional (3D) binder jet printing for making printed articles from powder. 
     BACKGROUND 
     Additive manufacturing (“AM”) processes generally involve the buildup of one or more materials to make a net or near net shape (NNS) object, in contrast to subtractive manufacturing methods. Though “additive manufacturing” is an industry standard term (ISO/ASTM52900), AM encompasses various manufacturing and prototyping techniques known under a variety of names, including freeform fabrication, 3D printing, rapid prototyping/tooling, etc. AM techniques are capable of fabricating complex components from a wide variety of materials. Generally, a freestanding object can be fabricated from a computer aided design (CAD) model. A particular type of AM process uses an irradiation emission directing device that directs an energy beam, for example, an electron beam or a laser beam, to sinter or melt a powder material, creating a solid three-dimensional object in which particles of the powder material are bonded together. Different material systems, for example, engineering plastics, thermoplastic elastomers, metals, and ceramics are in use. Laser sintering or melting is a notable AM process for rapid fabrication of functional prototypes and tools. Applications include direct manufacturing of complex workpieces, patterns for investment casting, metal molds for injection molding and die casting, and molds and cores for sand casting. Fabrication of prototype objects to enhance communication and testing of concepts during the design cycle are other common usages of AM processes. 
     Selective laser sintering, direct laser sintering, selective laser melting, and direct laser melting are common industry terms used to refer to producing three-dimensional (3D) objects by using a laser beam to sinter or melt a fine powder. More accurately, sintering entails fusing (agglomerating) particles of a powder at a temperature below the melting point of the powder material, whereas melting entails fully melting particles of a powder to form a solid homogeneous mass. The physical processes associated with laser sintering or laser melting include heat transfer to a powder material and then either sintering or melting the powder material. Although the laser sintering and melting processes can be applied to a broad range of powder materials, the scientific and technical aspects of the production route, for example, sintering or melting rate and the effects of processing parameters on the microstructural evolution during the layer manufacturing process have not been well understood. This method of fabrication is accompanied by multiple modes of heat, mass and momentum transfer, and chemical reactions that make the process very complex. 
     Another form of additive manufacturing involves the use of a binder to join the powder particles together, followed by subsequent sintering following the build process. The term “binder jetting” or “binder jet printing” describes a form of additive manufacturing that utilizes a printer to form three-dimensional objects from a powder by selectively applying a binder liquid to incremental layers of the powder. The binder binds layers of the powder into solid two-dimensional cross sections of the desired object, as well as binding layers to each other in the vertical direction. After fabrication of the part is complete, various post-processing procedures may be applied to the part. Post processing procedures include removal of excess powder by, for example, blowing or vacuuming. Other post processing procedures include a stress release process. Additionally, thermal and chemical post processing procedures can be used to finish the part. 
     There is an ongoing need to increase the operational speed of the AM apparatus, such that the throughput of the apparatus may be increased and the cost of each part may be reduced. Additionally, there is an ongoing need to improve the quality of the part built by the AM process. 
     BRIEF DESCRIPTION 
     Aspects and advantages will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     A binder jet printing apparatus is generally provided, along with methods of its use. In one embodiment, the binder jet printing apparatus includes: a job box having a actuatable build plate therein; a supply box having a bottom platform that is actuatable within the supply box; a print system including at least one print head connected to a binder source and configured to apply a pattern of binder onto an exposed powder layer over the build plate of the job box; a recoat system including a recoater configured to move from the supply box to the job box to transfer powder from the supply box to the job box so as to form a new powder layer over the build plate of the job box; and a cure system configured to direct electromagnetic radiation onto the job box. 
     In one embodiment, the build plate within the job box and the bottom platform within the supply box are actuatable in a shared relationship. For example, the job box and the supply box may have a substantially equal size in their respective x-y plane to have an equal volume per unit of depth in their respective z-direction. As such, when the bottom platform raises in the z-direction within the supply box for a first distance that is equal to or greater than a second distance that the build platform lowers within the job box, it is ensured that sufficient or excess powder is available to form a new powder layer over the job box. The print system may be configured to move over the job box independently of the movement of the cure system and the recoat system. 
     The cure system and the recoat system may be ganged together so as to move together. For example, the cure system and the recoat system may be positioned relative to each other such that, when passing from the supply box to the job box, the recoat system trails the cure system such that the binder on an exposed powder layer over the job box is cured prior to transfer of the new layer from the supply box to the job box. 
     The recoat system may include, in certain embodiments, a roller rotatable about an axis in a rotational direction that is counter-rotating to the direction of movement of the cure system from the supply box to the job box. For example, a controller may be included that is in communication with the roller and configured to regulate the rotational speed of the roller. In one embodiment, the roller is composed of a stainless steel with an external coating thereon that is configured to increase the hardness of the roller. The binder jet printing apparatus may also include a shield partially encasing the roller therein to help powder containment. 
     A drain system, an inner wall, and/or a cleaning system may also be included within the apparatus. The drain system may include a drain positioned along at least one side of the job box to collect excess powder from the job box. The inner wall may extend in the machine direction and may be positioned so as so separate the print system from the cure system and the recoat system. The cleaning system positioned such that a print head of the print system is cleaned simultaneously while the cure system and the recoat system are over the supply box and job box. 
     The process is also provided for binder jet printing to form a green component. In one embodiment, the process includes: printing a binder material onto a first layer of powder, which is positioned over a build plate within a job box, according to a specified design; curing the binder printed onto the first layer of powder; transferring powder from a supply box to the job box using a roller to form a second layer of powder over the first layer on the build plate; and repeating the printing, curing, transferring, and transferring to form the green component from multiple layers of powder cured together with the binder material. The roller moves in a machine direction from the supply box to the job box and rotates about an axis in a rotational direction that is counter-rotating to the direction of movement from the supply box to the job box. 
     These and other features, aspects and advantages will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain certain principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended FIGS., in which: 
         FIG. 1  shows a perspective view of an exemplary binder jet printing apparatus according to one embodiment of the present disclosure; 
         FIG. 2  shows side view of one aspect of an exemplary binder jet printing apparatus according to one embodiment of the present disclosure; 
         FIG. 3  shows a front view of an exemplary binder jet printing apparatus according to one embodiment of the present disclosure; 
         FIG. 4  shows top view of one aspect of an exemplary binder jet printing apparatus according to one embodiment of the present disclosure; 
         FIG. 5  shows an exemplary control system for use with the system and process for building an object according to one embodiment of the present disclosure (e.g., using a binder jet printing apparatus); 
         FIG. 6 a    shows a top view of an exemplary cleaning system for use with a binder jet printing apparatus such as in  FIGS. 1-4 ; 
         FIG. 6 b    shows a side view of the exemplary cleaning system of  FIG. 6 a   ; and 
         FIG. 7  shows the apparatus, such as in  FIGS. 1-4 , in a housing with an environmental system. 
     
    
    
     Repeat use of reference characters/terms in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. 
     When describing these drawings, coordinates are shown in the x-direction, the y-direction, and the z-direction. The x-direction may be referred to as the machine direction; the y-direction may be referred to as the cross-machine direction; and the z-direction may be referred to as the vertical direction (i.e., height). 
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     Apparatus and methods are generally provided for building a part(s) via binder jet printing. In certain embodiments, the apparatus and methods may provide improved throughput by reducing the amount of time required for a build compared to conventional binder jet printing apparatus. During the binder jet printing methods, a thin layer of powder is positioned over a build plate within a job box. A print system is utilized to spray a binder onto a thin layer of powder. A cure system is then used to set the binder (e.g., via curing) to form a layer of bound powder, in the configuration defined by the pattern the computer communicates to the print system for a given layer of an object. After the binder is set, the job box may be indexed down in the z-direction, and a recoat system may apply another thin layer of powder over the original layer. That is, after each layer is printed and cured, the work piece is indexed away from the print head for a sufficient distance to create room for a subsequent layer of powder while leaving the relationship between the print head and the subsequent powder layer, which may be the same as for the previous layer to provide a consistent spacing between the print head and each powder layer during the build. In particular embodiments, each powder layer has a thickness measured in the z-direction over the job box that is about 40 μm to about 75 μm, such as about 50 μm (e.g., 50 μm+/−5 μm). 
     This process of printing a binder, curing, indexing, and recoating is repeated for the desired number of layers to eventually form the part(s). The powder that was not patterned with the binder remains where it was originally deposited and serves as a foundation for powder/binder sections deposited in areas not previously patterned with binder, and as support for the powder/binder structure. When deposition of the part is complete, the powder not patterned with binder is removed leaving a green part formed from the powder held together by the binder. 
     Referring to  FIGS. 1-4 , embodiments of exemplary binder jet printing apparatus and methods are generally shown. Generally, the binder jet printing apparatus  10  of  FIGS. 1-4  includes a print system  12 , a cure system  14 , and a recoat system  16  to build a part  11  layer-by-layer within a job box  18  from a computer model (e.g., a CAD model stored within a control system  20 ). The part  11  may be a single component (i.e., an individual part) or multiple components (i.e., multiple individual parts). In the embodiments shown, the print system  12 , cure system  14 , and recoat system  16  are attached to a carry plate  22  that is moveable in the y-direction (i.e., the cross-machine direction), which is controlled by the first movement system  24 , over a work table  50 . As shown, the first movement system  24  controls the linear movement in the y-direction of the carry plate  22  along the support beams  26  that extend in the y-direction. As shown, the supports  27  attached to the carry plate  22  can move along the support beams  26 . Thus, the cross-machine movement in the y-direction of the print system  12 , cure system  14 , and recoat system  16  is performed together. Generally, the first movement system  24  may include any suitable components for linear movement of the carry plate  22  in the x-direction. For example, any combination of scaffold, gantry, beams, supports, motor, actuator, controls, rollers, positioning mechanism, etc. may be utilized. Likewise, the second movement system  28  and the third movement system  30  discussed below may include any suitable components for linear movement in the y-direction. 
     A second movement system  28  is attached to the print system  12  to independently control the movement of a print head  32  in the x-direction (i.e., the machine direction). Thus, the print system  12  may independently move in the x-direction across the print area  34  of the job box  18  (i.e., the top portion of the job box). 
     Generally, the print system  12  includes a print head  32  having one or more print dies  36 , each independently controlled and connected to a binder source  38 . In use, the first movement system  24  carries the carry plate  22  to a position in the y-direction such that the print head  32  is over at least a portion of the job box  18 . While moving in the x-direction, as controlled by the second movement system  28 , the print head  32  sprays a binder material  40  onto an exposed layer  42  of powder  44  within the job box  18  to according to the instructions from the control system  20 . Depending on the size of the print head  32  and/or the number of print heads  32  in the print system  12 , the print system  12  may make a single pass or multiple passes over the job box  18 . In one embodiment, the print head  32  has a plurality of independent print dies  36 , each configured to spray binder droplets having a drop volume of about 30 picoliters to about 80 picoliters. 
     After printing of the binder material  40 , a build plate  46  may be actuated within the job box  18  such that the build plate  46  moves down in the z-direction to allow for another powder layer to be applied over the build plate  46  within the job box  18 . In one embodiment, the distance that the build plate  46  moves in the z-direction is about 90% to 100% (i.e., equal to) the thickness of the powder layer  48  of each build layer to ensure that the powder layer  48  is fully and equally applied over build plate  46  within the job box  18 . A first actuation system  47  is associated job box  18  so as to control the movement of the build plate  46  in the z-direction. For example, if the powder layer  48  of each build layer is 100 micrometers (μm), then the build plate  46  of the job box  18  may be lowered away from the work table  50  for a distance of about 90 μm to 100 μm. 
     In the embodiment shown, the powder  44  is supplied from a supply box  54  that is positioned within the work table  50 . An second actuation system  52  is associated with a bottom platform  56  of the supply box  54  so as to control the movement of the bottom platform  56  in the z-direction. As such, the bottom platform  56  may be raised within the supply box such that loose powder  44  provides source powder for the recoat system  16  to create a new powder layer over the job box  18  (i.e., through moving the powder  44  from the supply box  54  to the job box  18 ). Although shown as independent actuation systems (one for each of the supply box  54  and the job box  18 ), the actuation may be performed in a shared relationship between the build plate  46  of the job box  18  and the bottom platform  56  of the supply box  54  with any suitable actuation mechanism(s). 
     In one embodiment, such as where the job box  18  and the supply box  54  have a substantially equal size in the x-y plane (and thus an equal volume per unit of depth in the z-direction) the distance that the bottom platform  56  raises in the z-direction within the supply box  54  is equal to or greater than the distance that the build plate  46  lowers within the job box  18  to ensure that sufficient or excess powder is available to form a new powder layer over the build plate  46  within the job box  18 . For example, if the powder layer  42  of each build layer is 100 micrometers (μm), then the bottom platform  56  may be raised within the supply box  54  for a distance of about 100 μm to 150 μm. 
     During the printing process, the cure system  14  and the recoat system  16  may be idle and/or positioned away from the job box  18  in the apparatus  10 . That is, the first movement system  24  moves the carry plate  22  in the y-direction such that the print system  12  is over the job box  18  while the recoat system  16  and the cure system  14  are positioned away from the job box  18  in the y-direction. Such a positioning of the carry plate  22  may be referred to as the first configuration, though it is understood that the carry plate  22  may not be stationary in the y-direction during the entire print process, since multiple passes in the x-direction (controlled by the second movement system  28 ) along different lines of the y-direction may be utilized to complete the printing process. Collectively, the first configuration refers to any position of the carry plate  22  where the print head  32  is positioned over at least a portion of the job box  18  in the y-direction. 
     After applying the binder material  40  onto the exposed layer  42  of powder  44  over the build plate  46 , the first movement system  24  moves the carry plate  22  to a second configuration, where the print head  32  is over a cleaning system  58  and where the cure system  14  and the recoat system  16  are positioned over the job box  18  in the y-direction. In one particular embodiment, the movement of the carry plate  22  by the first movement system  24  from the first configuration to the second configuration occurs simultaneous with the actuation of the build plate  46  within the job box  18  in the z-direction and of the bottom platform  56  within the supply box  54  in the z-direction. 
     Once the carry plate  22  is in the second configuration, the cure system  14  and the recoat system  16  may be passed over the job box  18  together in the x-direction, with the cure system  14  passing over the job box  18  first and the recoat system  16  trailing the cure system  14 . As such, the binder material  40  in the top, exposed layer  42  of powder  44  may be cured, followed by application of a new layer of powder  44  with the recoat system  16 . That is, the excess powder over the supply box  54  above the x-y plane of the top surface  51  of the work table  50  may be transferred to the job box  18  to form a new top layer with any excess powder being carried into the drain system  60  (e.g., for collection and recycling thereof). As shown, a series of drains  62  may be positioned along the sides of the supply box  54  and/or the job box  18  for collection of any excess powder  44  that is spread outside of the side edges  19  of the job box  18  and/or supply box  54 . In particular embodiments, the drain system  60  may be connected to a vacuum system  64  for collection of the excess powder  44 . 
     In the embodiment shown, a gang plate  66  carries the cure system  14  and the recoat system  16 . A third movement system  30  is attached to the gang plate  66  to control its movement in the x-direction such that the recoat system  16  and the cure system  14  move in unison in the x-direction, but independently in the x-direction from the print system  12 . Thus, the recoat system  16  and the cure system  14  may move in the x-direction across the print area  34  of the job box  18  independent of the x-direction movement of the print head  32 . 
     The cure system  14  may generally include a lamp  68  configured to direct electromagnetic radiation (i.e., light waves) onto the print area  34  of the job box  18 . In the embodiment shown, the lamp  68  spans the entire job box  18  in the y-direction. As such, the third movement system  30  may move the lamp  68  over the job box  18  in a single pass. During the movement of the lamp  68  over the job box  18 , the lamp  68  directs electromagnetic radiation onto the exposed layer  42  of powder such that any binder material  40  present therein may be dried and/or cured. For example, the electromagnetic radiation may have a wavelength and intensity sufficient to evaporate at least a portion of the solvent of the binder material  40  and/or cure non-volatile components (e.g., organic binding materials). 
     The lamp  68  may direct electromagnetic radiation having a wavelength in the microwave frequency, the infrared frequency, the visible frequency, the ultraviolet frequency, the x-ray frequency, the gamma ray frequency, etc., or combinations thereof. In one particular embodiment, the lamp  68  may direct light in the infrared frequency (e.g., having a wavelength of about 700 nm to about 1 mm), which may have sufficient energy to evaporate solvent from the binder material  40  and/or cure the binding material  40 . For example, such an infrared lamp may have a power of about 1000 W to about 2000 W. In one particular embodiment, the intensity of the lamp  68  is modulated by the controller  70  based on real-time temperature measurement of the job box  18 . For example, the controller  70  may obtain the temperature of the exposed layer  42  (e.g., using a temperature sensor  72 ) and determine the intensity of the lamp  68  required for the desired drying and/or curing operation at the particular speed of movement of the cure system  14  in the x-direction. In one embodiment, the controller  70  may utilize a closed loop control parameters that are determined by a computer model of the material system and process, thus alleviating the need for operator controller tuning through multiple iterations of trial and error. 
     The controller  70  may also actuate the operation of the lamp  68  (i.e., on/off) such that the lamp  68  is directing electromagnetic radiation only when traveling over the exposed layer  42  of the job box  18 . However, in particular embodiments, the controller  70  may do a “soft” start on the lamp  68  such that the intensity of the lamp  68  is slowly increased during each start up. Without wishing to be bound by any particular theory, it is believed that a “soft” start may extend the life of the lamp  68  and ensure uniform energy applied across the job box  18  during operation of the cure system  14 , both throughout each pass in the x-direction and between passes over subsequent layers of the build process. 
     The recoat system  16  trails the cure system  14  to transfer powder  44  from the supply box  54  to form a new powder layer  48  over the job box  18 . In the embodiment shown, the recoat system  16  includes a roller  74  that is rotatable about an axis  76  in a rotational direction that is counter-rotating (represented by arrow  81 ) to the direction of x-movement during recoating. As shown, the recoat system  16  is moving right to left in the x-direction, and the roller  74  is rotating in the clockwise direction (i.e. the counter rotating direction). In such an embodiment, the counter rotation of the roller  74  (with respect to the x-movement direction) creates a shear force on the powder layer  48  to force new powder and excess powder in front of the recoat system  16 , ensuring sufficient pick-up of the powder  44  from the supply box  54  and uniform application of the powder  44  across the entire x-y plane of the job box  18 . Without wishing to be bound by any particular theory, it is believed that the counter rotation of the roller  74  generates shear forces that help overcome cohesive forces within the powder  44  being pushed across the job box  18 . 
     A controller  78  is shown to regulate the rotational direction and/or speed of the roller  74  as it is moved in the x-direction. The controller  78  may be connected to the roller  74  via any rotational mechanism (e.g., a belt drive). 
     The roller  74  may have a substantially smooth surface  80  across its entire surface, with minimal surface imperfections or linear bending/distortion across the length of the roller  74 . For example, the roller  74  may be made from a relatively hard material (e.g., stainless steel). The roller  74  may be a solid roller, or may be a hollow roller with end caps (e.g., to reduce weight of the roller). The roller  74  may also have a temperature regulator device  82  (e.g., a heating device and/or a cooling device) to set a desired roller surface temperature. An external coating  84  may be on the surface  80  of the roller  74  to adjust the surface properties of the roller  74  for contacting the powder layers  48 . For instance, the coating  84  may increase the hardness of the surface  80  of the roller  74 , and/or reduce the surface energy of the roller  74  so as to reduce the adhesive tendency between the roller surface  80  and the powder  44  (including dry powder and/or binder-infiltrated powder). 
     Suitable coating materials may include, for example, thin dense chromium coating (e.g., formed of Armoloy® TDC (Armoloy of Western Pa., Inc., Pennsylvania), aluminum infiltrated with polytetrafluoroethylene (e.g., Teflon® (The Chemours Company, Delaware), etc. In one embodiment, the coating  84  may have a thickness (i.e., extending in a radial direction from the axis  76  of the roller  74 ) of about 0.1 μm to about 1000 μm (e.g., about 1 μm to about 25 μm, such as about 2 μm to about 10 μm). 
     In one embodiment, after the recoat system  16  completes its first pass over the job box  18 , the roller  74  may be traversed back over the applied new powder layer  48  to compress the powder  44  over the job box  18 . In such an embodiment, the speed of the traverse pass may be matched to the rotation of the roller  74  such that shear forces on the powder layer  48  is minimized. Without wishing to be bound by any particular theory, the roller  74  may compress the newly applied powder layer  48  to improve the powder layer  48  for subsequent binder application thereon. For instance, it is believed that the traversal of the roller  74  over the job box  18  during this second pass allows the roller  74  to generate normal forces that both push the powder  44  forward as well as down into the region between the roller  74  and the surface of the previously exposed layer  42 . 
     The rotation speed and x-direction movement speed may vary depending on the size of the supply box  54  and the job box  18 , the size of the roller  74  (e.g., the diameter), the material of the powder  44 , etc. In one embodiment, the rotational speed of the roller  74  may be about 100 rotations/minute (RPM) to about 1000 RPM in the counter rotational direction, while the speed of the roller  74  in the x-direction is about 25 mm/s to about 300 mm/s across the job box  18  in the x-direction. 
     Optionally, a shield  86  may be utilized in conjunction with the roller  74  to partially encase the roller  74  therein and to help powder containment within the build area (e.g., between the drains  62 ). Also optionally, a vacuum manifold  88  may be positioned in close proximity to the roller  74  to pick up aerosolized powder particles  44  during the recoating process. Such a vacuum manifold  88  and/or shield  86  may be particularly useful when spreading a powder  44  having relatively small particle sizes. In particular embodiments, such a vacuum manifold  88  may form part of an internal environmental monitoring or control system. 
     While the carry plate  22  is in the second configuration, the print head  32  is positioned over a cleaning system  58 . The cleaning system  58  may remove any excess binder and/or powder that has attached onto the print head  32 , and particularly the print die(s)  36  within the print head  32 . In one particular embodiment, the print head  32  is cleaned simultaneously while the cure system  14  and recoat system  16  are operating over the job box  18 . In such an embodiment, the spacing between the cleaning system  58  and the job box  18  in the y-direction is substantially the same as the spacing between the print system  12  and the cure system/recoat system ( 14 / 16 ) on the carry plate  22 . In a preferred embodiment, the print system  12  and cure/recoat systems ( 14 / 16 ) are mechanically separated (e.g., by an inner wall  90 ) in order to confine heat &amp; powder from contaminating the cleaning system  58  as well as stray binder/cleaner from entering the supply box  54  and/or job box  18 . As shown, the inner wall  90  extends in the x-direction and is positioned so as to separate the print system (on one side of the inner wall  90 ) from the cure system and the recoat system (on the opposite side of the inner wall  90 ). 
       FIGS. 6A and 6B  show various view of an exemplary embodiment of the cleaning system  58 , which may include one or more of a waste purge area  92 , a wiping station  94 , a sponge station  96 , and a pattern test station  98 . Wiping stage(s) may be performed by moving the print head  32  in the x-direction over the wiper station  94  such that the die(s)  36  of the print head  32  contact a wiper  100  within the wiping station  94 . In one embodiment, the wiper  100  may be actuated in the z-direction within the wiper station  94  such that the wiper  100  is wet with a cleaning solution through at least one pass of the print head  32  (e.g., the first pass of the print head  32  over the wiper  100 ). Thus, the wet pass may ensure that the print die(s)  36  of the print head  32  contact the cleaning solution during the cleaning process. The print head  32  may also pass over the wiper  100  again, without re-wetting the wiper, such that the print head  32  makes a dry pass to remove loose material and/or residual cleaning solution thereon. Before and/or after the wiping stages, the print head  32  may be moved in the x-direction over the waste purge area  92 . There, the print head  32  may be activated to spray binder material  40  out of the print die(s)  36  of the print head  32  to help clear the die(s)  36 . When the apparatus is idle (e.g., between build projects), the print head  32  may be positioned onto a sponge  97  within the sponge station  96 , which remains wet with the cleaning solution via capillary action from the bath. The sponge  97  may be, in particular embodiments, a porous foam preferentially selected to be compatible with binder, cleaner, and/or print head (e.g., a polyurethane foam). Thus, the die(s)  36  of the print head  32  may remain unclogged for subsequent use. A pattern test station  98  may be adjacent to the cleaning system  58  to allow for test printing through the print head  32  to ensure that each of the dies  36  are unclogged and in good working order prior to each print project. 
     Referring again to  FIGS. 1-4 , an inner wall  90  may extend from the carry plate  22  between the print system  12  and the cure system/recoat system ( 14 / 16 ) to help isolate the independent operations. Thus, the cleaning operation of the print head  32  over the cleaning system  58  may be separated from the environment over the job box  18  while the recoat system  16  is transferring powder  44  from the supply box  54  to the job box  18 . 
     Referring to  FIG. 3 , an optional positioning system  102  may be utilized to help control the movement of the first movement system  24 , a second movement system  28 , and a third movement system  30 . When present, the positioning system  102  may be in communication with the control system  20 . 
     In the embodiment shown in  FIG. 7 , the apparatus  10  may be encased within a housing  104 . For example, the housing  104  may encapsulate the job box  18 , the print system  12 , the cure system  14 , the recoat system  16 , the cleaning system  58 , and optionally other components of the apparatus  10  in order to facilitate control of the build environment. The housing  104  may help with powder containment within the apparatus  10 . In one particular embodiment, an environmental system  106  is utilized in conjunction with the housing  104 . The environmental system  106  may include a filter system  108  configured to collect aerosolized powder particles within the apparatus  10 , as well as to extract fumes and other volatile species created during the build process. 
     The output of the apparatus  10  shown in  FIGS. 1-4  may be a green part formed of the build powder with the cured binder material that retains the portion in the green shape produced. The build powder may be any suitable powder (e.g., metal, metal alloy, ceramic, and so forth, as well as combinations thereof). The binder may be any suitable liquid binder. 
     Upon completion of the green part, post processing steps may be performed to transform the green part into the finished part. Post processing steps may include, but are not limited to, cleaning, heat treatment (e.g., to drive away binder from the green part), infiltration, etc. For example, heat treatment may also include solid-state sintering of the powder after binder removal as well as hot isostatic pressing (HIP) to get to full density monolithic parts. 
       FIG. 5  depicts a block diagram of an exemplary control system  200  that can be used to implement methods and systems according to example embodiments of the present disclosure, such as the control system  20 , the controller  70 , the controller  78 , etc. In particular, the control system  200  may control one or more of the first movement system  24 , the second movement system  28 , the third movement system  30 , the positioning system  102 , the cure system  14 , the recoat system  16 , the print system  12 , the cleaning system  58 , the actuation system  47  for the job box  18 , the actuation system  52  for the supply box  54 , the drain system  60 , operation of the lamp  68 , operation of the roller  74 , etc. 
     As shown, the control system  200  may include one or more computing device(s)  202 , which may operate independently from each other or in communication with each other (e.g., wired communication, wireless communication, etc.). The one or more computing device(s)  202  can include one or more processor(s)  204  and one or more memory device(s)  206 . The one or more processor(s)  204  can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, or other suitable processing device. The one or more memory device(s)  206  can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, or other memory devices. Control parameters may also come from a network, including but not limited to server-operated controllers (i.e., cloud), such that the apparatus may be operated remotely. 
     The one or more memory device(s)  206  can store information accessible by the one or more processor(s)  204 , including computer-readable instructions  208  that can be executed by the one or more processor(s)  204 . The instructions  208  can be any set of instructions  208  that when executed by the one or more processor(s)  204 , cause the one or more processor(s)  204  to perform operations. The instructions  208  can be software written in any suitable programming language or can be implemented in hardware. In some embodiments, the instructions  208  can be executed by the one or more processor(s)  204  to cause the one or more processor(s)  204  to perform operations, such as the operations for the first movement system  24 , the second movement system  28 , the third movement system  30 , the positioning system  102 , the cure system  14 , the recoat system  16 , the print system  12 , the cleaning system  58 , the actuation system  47  for the job box  18 , the actuation system  52  for the supply box  54 , the drain system  60 , the lamp  68 , the roller  74 , etc., shown in  FIGS. 1-4 . 
     The memory device(s)  206  can further store data  210  that can be accessed by the one or more processor(s)  204 . For example, the data  210  can include any data used for a build process, such as a CAD model as described herein. The data  210  can include one or more table(s), function(s), algorithm(s), model(s), equation(s), etc. for stabilizing input according to example embodiments of the present disclosure. The one or more computing device(s)  202  can also include a communication interface  212  used to communicate, for example, with the other components of the apparatus  10 . The communication interface  212  can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, or other suitable components. 
     This written description uses exemplary embodiments to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.