Patent Publication Number: US-2023150203-A1

Title: Methods And System For Removal Of Powder From An Additively Manufactured Part

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to U.S. provisional patent application Ser. No. 63/010,464, filed on Apr. 15, 2020. 
    
    
     FIELD OF THE INVENTION 
     This disclosure relates generally to additive manufacturing and in particular to a system and method for removing unwanted material from parts made by a 3D printer in a printing stage of the overall additive manufacturing process. 
     BACKGROUND OF THE INVENTION 
     In some kinds of additive manufacturing processes (also referred to as 3D printing processes), such as Selective Laser Sintering (SLS), Electron Beam Melting (e-beam), Multi-Jet Fusion (MJF), or Powder Bed Fusion (PBF), solid objects are manufactured using a computer-controlled beam or print head to fuse or solidify portions (such as the walls) of the object a layer at a time until the entire three-dimensional object is formed. After the solid three-dimensional object is formed, unwanted material, such as a powder from which the object was formed, may cling to or encase the solid object. It is necessary to remove this unwanted material from the solid printed object before the next step, which may include painting, curing, passivation, coating, assembly, and so on. Removal of unwanted powder material from additively manufactured parts is sometimes referred to as decaking or depowdering. In some additive manufacturing processes, printed objects have unwanted support material on them after the printing stage. Some additively manufactured objects may have rough surfaces or build lines after being formed by the printer. Finishing processes are needed to remove unwanted material, such as powder or support material, or to smooth rough surfaces of additively manufactured objects. 
     Additional disclosure about techniques and processes for additive manufacturing and removal of unwanted material from objects formed by additive manufacturing can be found in copending patent applications, US20190176403, US20190202126, US20190270248, US20190275745, US20190315065, US20170348910, and PCT/US2020/041396, which are assigned to the owner of the present application and the entire disclosures of which are incorporated by reference herein. 
     SUMMARY OF THE INVENTION 
     A system and method are disclosed for removal of unwanted material from additively manufactured parts by application of vibratory and/or acoustic energy. The system and method include a vibratory platform located in a chamber. Additively manufactured parts having unwanted material adhered thereto are placed on the vibratory platform. The platform is caused to vibrate thereby causing the unwanted material to detach from the parts. The system and method may also include the application of acoustic energy to cause unwanted material to detach from the parts. The unwanted material removed from the additively manufactured parts can be collected and recycled. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG.  1    is a perspective view showing an embodiment of a system for removing unwanted material from additively manufactured parts. 
         FIG.  2    is a cutaway side view of the embodiment shown in  FIG.  1   . 
         FIG.  3    is a flowchart showing an embodiment of a process performed by the system of  FIGS.  1  and  2    for removing unwanted material from additively manufactured parts. 
         FIG.  4    shows the embodiment of  FIG.  2    at a stage of the process of  FIG.  3   . 
         FIG.  5    is a cutaway side view of another embodiment of a system for removing unwanted material from additively manufactured parts. 
         FIG.  6    is a flowchart showing a process performed by the system of  FIG.  5   . 
         FIGS.  7 A and  7 B  are perspective views of a portion of another embodiment of a system for removing unwanted material from additively manufactured parts. 
         FIGS.  8 A,  8 B, and  8 C  depict different types of vibrations that can be used in the embodiments disclosed herein. 
         FIG.  9    is a cutaway side view of another embodiment of a system for removing unwanted material from additively manufactured parts. 
         FIG.  10    shows a side view of an outside of the system shown in  FIG.  9   . 
         FIG.  11    show a perspective view of the processing platform in the system shown in  FIG.  9   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the invention will be described in terms of certain examples, other examples, including examples that do not provide all of the benefits and features set forth herein, are also within the scope of the invention. Various changes to the system and method may be made without departing from the scope of the invention. 
     An embodiment of a system  200  for removing unwanted material from additively manufactured parts (also referred to herein as “objects”) is shown in  FIG.  1   . The system  200  includes a chamber  202  and an adjacent enclosure  204 . The chamber  202  has a door  208  that can be opened and closed. The door  208  provides access to a chamber interior  210  (shown in  FIG.  2   ). The door  208  includes a seal around it to prevent or reduce air, powder, or sound leakage from the chamber  202 . The chamber  202  has a size suitable for containing therein additively manufactured parts (also referred to as “objects”), including the unwanted material formed in that portion of the additive manufacturing process performed by a 3D printer. The chamber  202  and the door  208  may be made of a suitable, durable material such as plastic, metal (e.g., stainless steel, polycarbonate), or a combination thereof. The chamber  202  also includes a viewing pane  209 . The viewing pane  209  is composed of a transparent material such as glass or plastic. The viewing pane  209  enables an operator to view the chamber interior  210 . The viewing pane  209  is located in a wall of the chamber. In one embodiment, the viewing pane  209  is located in the chamber door  208 . 
       FIG.  2    shows a cutaway view of the chamber  202 . Located in the interior  210  of the chamber  202  is a platform  212 . The platform  212  is made of a durable material. Suitable materials include a metal, such as stainless steel, aluminum, plastic, cardboard, or paper. The platform  212  is sized and adapted for having placed thereupon one or more parts  214  that had been formed by an additive manufacturing process, such as SLS. In one embodiment, the platform  212  is circular with a diameter of approximately 25 cm (10 inches) although other sizes are suitable. In this embodiment, the parts  214  are approximately 2.4 to 4 grams. The quantity of parts  214  that can be placed on the platform  212  and finished at one time can vary. In this embodiment, between 6 and 110 or more or fewer parts can be placed on the platform  212  and finished at one time. Other quantities may also be suitable. When formed by the additive manufacturing process, the parts  214  have unwanted material  216  remaining thereupon. In this example, the unwanted material  216  is a nylon powder. Further, when formed by this additive manufacturing process, the parts  214  may be encased in the unwanted powder material  216 . 
     As shown in  FIG.  2   , an interior wall  218  of the chamber  202  is spaced from an outer wall  219 . In this embodiment, the interior wall  218  extends around the entire perimeter of the interior  210  of the chamber  202  spaced inward from the outer wall  219 . The interior wall  218  defines an inner portion of the interior  210 . In this embodiment, the inner wall  218  is open on a top side. The platform  212  is mounted in the chamber  202  so that it is spaced from the interior wall  218 , thereby forming a gap  220  between an edge of the platform  212  and the interior wall  218 . The gap  220  does not need to extend around the entire perimeter of the platform  202 . The gap  220  has a size narrow enough to prevent any of the objects  214  located on the platform  212  from falling though the gap  220 , but wide enough so that any unwanted material  216  detaching from the objects  214  can pass though the gap  220  during the finishing process. In one embodiment, the gap  220  is approximately 1.27 cm (½ inch), but other sizes may be suitable depending on the size of the parts to be placed on the platform  212 . 
     The platform  212  is mounted in the chamber  202  so that it can move (i.e., vibrate). This can be accomplished in various different ways. One suitable way is to make the connection between the platform  212  and the chamber  202  a flexible connection. Another way is to provide a hinged or loose connection. Another way is to provide a solid fixed rim  224  that is fixed to the chamber outer wall  219 , but which has a flexible connection to a middle portion of the platform  212 , similar to a speaker diaphragm. 
     Connected to the underside of the platform  212  is a transducer  222 . The transducer  222  is operatively connected to the platform  212  to impart vibrations to it. In one embodiment, the transducer is an electromagnetic coil. The transducer  222  is connected to a power source  228  by means of a wire or cable  230 . The power source  228  is located outside the chamber  202  in the enclosure  204  located adjacent to the chamber  202 . The cable  230  extends through the walls of the chamber  202  and the enclosure  204  to connect the transducer  222  to the power source  228 . In one embodiment, the power source  228  is an amplifier. 
     In the enclosure  204  is a control unit  236 . In alternative embodiments, the control unit  236  may be located remotely. The control unit  236  is operatively connected to the hardware of system  200 , including the power source  228 . In one embodiment, the control unit  236  is a personal computer (PC) running a suitable operating system, such as the Windows® operating system. Alternatively, the control unit  236  may be any other computing platform, including a smartphone running Android or iOS. In one embodiment, the control unit  236  and power source  228  are combined into one unit. 
     The control unit  236  includes appropriate programming  240  by which the system  200  can be operated, as explained below. 
     Connected to the control unit  236  is a user interface  242 . The user interface  242  includes a touch screen or other hardware for receiving input from a (human) user operator and providing an information output to the user operator. In the embodiment shown in  FIG.  2   , the user interface  242  is shown located on the enclosure  204 . In alternative embodiments, the user interface  242  may be located elsewhere, including remotely. 
     Located in the bottom floor of the chamber  202  is a discharge chute  244 . The discharge chute  244  connects to a discharge exhaust  246  for removing the unwanted material  216  that is removed from the parts  214 . The exhaust  246  is connected to a vacuum or suction to withdraw the unwanted material  216  from the chamber  202 . A filter system (not shown) may be included in-line with the exhaust  246  to catch particles. 
     Operation 
       FIG.  3    shows a flowchart of a process  250  performed by or with the system  200  of  FIGS.  1  and  2   . In step  254 , the objects  214 , which had been manufactured by an additive manufacturing process and which are encased in unwanted material (e.g., powder)  216 , are placed in the system  200 , specifically on the platform  212  inside the chamber  202 . 
     Next, solid abrasive media  256  is placed on the platform  212  (Step  258 ). This step is optional and may be omitted in some embodiments. The solid abrasive media  256  can be mixed or interspersed with the parts  214 . In one embodiment, the solid abrasive media  256  is UPM. In another example, plastic acrylic media particles having an irregular shape are used. Other kinds of solid abrasive media may be suitable, including M-CAT. The amount of solid abrasive media  256  placed on the platform is dependent on the quantity and sizes of the parts  214 . In one embodiment, approximately ½ cup of solid abrasive media  256  is used. After the parts  214  encased in unwanted material  216  and the solid abrasive media  256  are placed on the platform  212  in the chamber  202 , the door  208  is closed. 
     The control unit  236  is operated (e.g., by means of the user interface  242 ) to cause the power source  228  to energize the transducer  222  thereby causing the platform  212  to vibrate (Step  260 ). There are different kinds of vibration that can be applied to the vibratory platform  212 .  FIGS.  8 A,  8 B, and  8 C  depict different types of vibrations that can be applied to the platform  212 . (The depictions in  FIGS.  8 A,  8 B and  8 C  are not necessarily to scale. These types of vibrations are not the only types that can be applied and other types may be suitable.) In  FIG.  8 A , a uniformly vertical vibratory action is depicted. In this type of vibration, the platform surface moves uniformly across its width with an up and down motion, similar to an audio speaker.  FIG.  8 B  shows the platform  212  vibrating with a sinusoidal motion, in which parts of the platform move upward while other parts move downward at the same time. This type of vibration is characteristic of Chladni plates in which locations of movement are separated by relatively stationary locations, corresponding to nodes of relative stability.  FIG.  8 C  shows another type of vibratory motion in which the platform  212  moves with a trampoline-type of motion, with a central portion having a large amplitude with the amplitude diminishing toward the edges. 
     An objective in selecting a type of vibration (as well as selecting a waveform, frequency and amplitude of vibration) is to separate the additively manufactured parts from the unwanted material attached thereto. One way to effect this separation is to impart disparate movement between the additively manufactured parts and the unwanted material, thereby causing the unwanted material to detach from the additively manufactured parts. In some cases, the type of vibratory action is selected to impart a resonance with either the additively manufactured parts or the unwanted material, but not both. For example, a vibration can be selected that causes the unwanted material to resonant at a certain frequency, but that causes the additively manufactured parts to not vibrate at all. In another case, the type of vibratory action is selected to impart a resonance with the additively manufactured parts at a first frequency and to impart a resonance with the unwanted material at a second, different frequency. Thus, causing the additively manufactured parts or the unwanted material to vibrate differently from the other can effect detachment of the unwanted material from the additively manufactured parts. Further, selection of an appropriate vibration can also cause the unwanted material to move away from the additively manufactured parts and even cause the unwanted material to move off the platform, in a manner similar to how powder can be caused to accumulate at nodes on a Chladni plate. 
     Reference is made to applications in cymatics that address and describe wave phenomena. The selection of the type of vibration, the type of waveform, the frequency and amplitude of vibration, the duration of vibration, and whether different types of waveforms, frequencies, or amplitudes are used depends on several factors. These factors include the material composition of the additively manufactured parts, the sizes and geometry of the additively manufactured parts, the amount of unwanted material attached to the additively manufactured parts, and other factors. 
     Referring again to  FIG.  3   , in this embodiment, the power source  228  applies a sinusoidal wave to the transducer  222 . In alternative embodiments, other types of waveforms may be suitable. In this embodiment, the platform  212  is vibrated at a frequency of between 75 and 135 Hertz, although other frequencies may be suitable. The platform  212  is vibrated for a period of time. In this embodiment, the platform  212  is vibrated for  30  minutes. Other durations of time may be suitable. While the platform  212  is being vibrated, the vibration of the platform  212  is transferred to the parts  214  and the unwanted material  216  located on the platform  212 , Movement is imparted between the parts  214  and the unwanted material  216 . The vibration of the vibratory platform  212  causes the unwanted material  216  to detach from the parts  214 . The solid abrasive media  254 , shaking among the parts  214 , helps with this process. In cases in which the parts  214  are relatively small, the vibratory amplitude large, or the vibratory frequency low, the parts  214  may bounce on the platform  212 . In cases in which the parts  214  are relatively large, the vibratory amplitude small, or the vibratory frequency high, the parts  214  may remain relatively stationary on the platform  212 . As the vibratory action continues, some or all the unwanted material  216  that has detached from the parts  214  eventually moves or bounces to the edge of the platform  212  and falls through the gap  220  to the bottom of the chamber  202 , as shown in  FIG.  4   . Some or all the abrasive material  254  may also fall to the bottom of the chamber  202 . Because the parts  214  are too large to fall through the gap  220 , they remain on the platform  212 , As the unwanted material  216  accumulates at the bottom of the chamber  202 . it can be evacuated through the chute  244  and exhaust  246  by suction or other means (Step  262 , in  FIG.  3   ). 
     Referring to  FIG.  3   , the parts  214  can be examined to determine if the unwanted material has been sufficiently removed (Step  264 ). This step may be performed manually (e.g., by an operator) by stopping the vibration and examining the parts  214 . Alternatively, this step may be performed using machine vision, or other automatic processes. If it is determined that the parts  214  need more finishing, the parts  214  are placed again on the platform  212  and the platform  212  is vibrated again (Steps  266  and  260 ). The parts  214  may be rotated or moved on the platform  212  to facilitate powder removal. The steps of vibrating the parts  214  on the platform  212  and then examining them may be conducted as many times as needed. 
     Upon examination, if it is determined that the parts  214  are sufficiently finished (e.g., sufficient unwanted material  216  has been removed), the parts  214  can be removed from the chamber  202  (Steps  266  and  268 ). The unwanted material  216  that had been removed from the parts  214  is recycled or otherwise disposed of (Step  270 ). Then, the process  250  ends. The parts  214  are ready for the next stage, which may include further powder removal, curing, washing, painting, passivation, assembly, and so on. 
     Alternative Embodiments 
     First Alternative Embodiment 
       FIG.  5    shows another embodiment of a system for removing unwanted material from additively manufactured parts. In  FIG.  5   , a system  300  includes components that are similar to those described in connection with the embodiment of the system  200  shown in  FIGS.  1 ,  2 , and  4   . The system  300  includes a chamber  302  having a door (not shown, but similar to the door  208  in  FIG.  1   ) and an adjacent enclosure  304 . Located in an interior of the chamber  302  is a platform  312 , sized and adapted for having placed thereupon additively manufactured parts  314  that have unwanted material (e.g., nylon powder)  316  remaining thereupon and encasing in the parts  314 . 
     The platform  312  is spaced from an interior wall  318  of the chamber  302 , by a gap  320 . A transducer (or actuator)  322  is operatively connected to an underside of the platform  312  to impart vibrations to it. The transducer  322  is connected by a cable  330  to a power source  328  located in the enclosure  304 . A control unit  336  is operatively connected to the hardware of system  300 , including the power source  328  and a user interface  342 . The control unit  336  includes appropriate programming  340 . A discharge chute  344  is located in the bottom floor of the chamber  302  and connects to a discharge exhaust  346 . 
     The system  300  also includes one or more cameras  350 . The cameras  350  are located in the chamber  302  adjacent to and/or above the platform  312 . The cameras  350  are connected to the control unit  336  by appropriate means, such as cabling. The cameras  350  are oriented and adapted to obtain imagery (including video) of the interior of the chamber  302  including anything located on the platform  312  such as the parts  314 , the unwanted material  316 , and the solid abrasive media  356 , if any. 
     The system  300  also includes one or more additional sensors  352 . The additional sensors  352  are located in the chamber  302  adjacent to and/or above the platform  312 . These additional sensors  352  are connected to the control unit  336  by appropriate means, such as cabling. These additional sensors  352  may include one or more microphones, thermometers, accelerometers, scanners, radar, lidar, and so on. These additional sensors  352  are adapted to measure properties of anything on the platform  312  or in the chamber  302 . 
     The system  300  also includes a scale  354 . The scale  354  is located in the chamber  302  and connected to the control unit  336  by appropriate means, such as cabling (not shown). The scale  354  is adapted to measure the weight of anything located on the platform  312  and provide data indicative thereof to the control unit  336 . 
     The system  300  also includes a cyclone generator  360 . The cyclone generator  360  connects to the interior of the chamber  302  by means of one or more inlet ducts or tubes  362 . The cyclone generator  360  is connected to a source of air, such as ambient air. The cyclone generator  360  provides flow of air through the interior of the chamber  302 . The cyclonic generator  360  may include an electric driven impeller or blower to create the air flow. The inlet ducts  362  are located and arranged to create a circular, cyclonic airflow within the chamber  302 . The cyclone generator  360  is operatively connected to and operates under the control of the control unit  336 . In one embodiment, the cyclonic generator  360  provides suction (negative pressure) in a vertical direction to remove loose unwanted powder  316 . The cyclonic generator  360  may force unwanted powder  316  towards the top or bottom of the chamber  302 . 
     Mounted in the chamber  302  are one or more audio transducers  366 . The audio transducers  366  may be horns, speakers, diaphragms, vibratory plates or membranes, or other devices capable of forming audio (i.e., sonic, acoustic) waves. The audio transducers  366  are adapted to provide audio waves in the air inside the chamber  302 . The audio transducers  366  are adapted to provide audio waves at different frequencies and amplitudes based on signals input thereto. In this embodiment, the audio transducers  366  are mounted and oriented to project audio waves at the parts  314  and unwanted material  316  on the platform  312 . The audio transducers  366  are operatively connected to an amplifier  368 , which in turn is connected to the control unit  336 . 
     The system  300  also includes a profile database  370 . The profile database  370  is a data storage adapted to contain various different operational profiles or recipes. The operational profiles are comprised of stored data that includes operating parameters for different parts to be placed in the system  300  for removal of unwanted material. The profile database  370  is operatively connected to the control unit  336 . The profile database  370  may be located with the control unit  336  in the housing  304  or may be located remotely. The profile database  370  is adapted to exchange data with the control unit  336 . 
     Operation 
       FIG.  6    shows a flowchart of a process  400  performed by or with the system  300  of  FIG.  5   . In step  402 , the objects  314 , which had been manufactured by an additive manufacturing process and which are encased in unwanted material (e.g., powder)  316 , are placed on the platform  312  inside the chamber  302 . 
     Next, solid abrasive media  356  is placed on the platform  312  and mixed or interspersed with the parts  314  (Step  404 ). At this point, the door  308  of the chamber  302  is closed. 
     If the system  300  is to be operated in automatic mode, a profile can be selected (Step  406 ). This step is optional. A profile can be selected using the user interface  342 . Profiles are stored in the profile database  370 . An appropriate profile can be selected based on matching parameters, such as the type of material from which the parts are made, the quantity of parts in the chamber  302 , the dimensions of the parts, the geometry of the parts, desired finish properties, and so on. A new profile can also be generated from characteristics and prior history of finishing operations. Alternatively, the system  300  can be operated in a manual mode in which the operating characteristics, such as the air flow, vibrating frequency, vibrating amplitude, temperature, acoustic energy, duration, and so on, are selected by an operator via the user interface  342 . 
     Depending on the operating characteristics chosen, one or more of the following steps are performed. A vibratory motion is applied to the platform  312  (Step  408 ). The cyclone generator  360  is operated to create a cyclonic airflow in the chamber (Step  410 ). The acoustic transducer(s)  366  are operated to create sonic waves that impact the parts  314  and unwanted material  316  (Step  414 ). Unwanted material  316  that falls to the bottom of the chamber  302  is evacuated via the chute  344  and exhaust  346  (Step  416 ). The parts  324  are evaluated to determine the progress of the removal of the unwanted material  316  (Step  418 ). This evaluation step may be performed after a duration of time, regularly, intermittently, or continuously. This evaluation step may be performed using input from the scale  354 , the cameras  350 , the other sensors  352 , direct visual observation, or other means. The evaluation step may be performed with the assistance of software tools, such as image recognition or machine vision programming that evaluates the progress of the removal of the unwanted material. These steps (Steps  408 ,  410 ,  414 ,  416 ,  418 ) may be performed all at once, or may be performed in a stages one or more at a time, in overlapping stages or non-overlapping stages, or may be performed cyclically, on-off, intermittently, or according to another scheme or routine. 
     After the unwanted material  316  is sufficiently removed, the parts  314  are removed from the chamber  302  (Step  420 ). The unwanted material  316  which has been evacuated via the exhaust  346  is recycled or otherwise disposed of (Step  422 ). 
     Second Alternative Embodiment 
       FIGS.  7 A and  7 B  show another alternative embodiment of a system  500  for removing unwanted material from additively manufactured parts. Referring to  FIGS.  7 A and  7 B , a chamber  502  includes a vibratory platform  512 . Parts (not shown) to be cleaned (decaked) can be placed on the vibratory platform  512 . The vibratory platform  512  is mounted in a slidable tray  513  that enables the vibratory platform  512  to be slid from a position outside the chamber  502  (as shown in  FIG.  7 A ) into a position inside the chamber  502  (shown in  FIG.  7 B ). The slidable tray  513  enables the vibratory platform  512  to be slid into a position outside the chamber  502  to facilitate placing parts onto the vibratory platform  512  and inspecting the parts to evaluate the progress of removal of unwanted material. This enables an operator to remove some parts that are finished, leave other parts that need more processing on the platform  512 , and add additional parts if there is room on the platform  512 . In  FIGS.  7 A and  7 B , the unwanted material that is removed from the additively manufactured parts falls off the vibratory platform  512  to a lower chamber portion  508 . The lower chamber portion  508  is mounted in a slidable tray  509  that enables the lower chamber portion  508  to be slid from a position outside the chamber  502  (as shown in  FIG.  7 A ) into a position inside the chamber  502  (shown in  FIG.  7 B ). The embodiment  500  shown in  FIGS.  7 A and  7 B  also includes glove ports  511  for using gloves (not shown). Gloves enable an operator to examine (through a viewing pane, not shown) and arrange parts on the platform  512  without opening the chamber  502 . The embodiment of the system  500  in  FIGS.  7 A and  7 B  can be operated in a manner similar to the system  200  shown in  FIGS.  1 ,  2 , and  4    or the system  300  shown in  FIG.  5   . 
     Third Alternative Embodiment 
       FIGS.  9  and  10    show another alternative embodiment.  FIGS.  9  and  10    show a system  600  for removing powder from additively manufactured objects. The system  600  uses processes similar to the other embodiments disclosed herein to remove powder from 3D printed objects. The system  600  includes additional components and features including features that facilitate handling and transfer of objects encased in powder from a 3D printer that produced the objects. 
     The system  600  includes a housing  602  that contains multiple compartments and chambers, as described herein. The system  600  includes a control panel  601 . The control panel  601  is located at a side of the housing  602  in an enclosure  603  or alternatively the control panel  601  can be located elsewhere at a convenient location on or in the housing  602 . The control panel  601  includes a user interface. The user interface enables an operator to input instructions, commands, parameters, and other information into the system  600  as well as receive information and other output from the system  600 . The control panel  601  is connected to a controller of the system  600 . 
       FIG.  9    shows the housing  602  with its front panels removed. Inside the housing  602  is a receiving area  604 . The receiving area  604  has a size and dimensions to receive therein an exchangeable printing frame  606 . The exchangeable printing frame  606  is a component used in a 3D printer that uses powder bed technology to produce objects. The exchangeable printing frame  606  is a box-like structure comprised of outer side walls  607  with an open upper side and a bottom floor comprised of a movable platform  605  that can translate vertically up and down within the outer side walls  607 . 
     In a powder bed 3D printer, an object is printed in a printing frame a layer at a time. In a 3D printer, with the platform  605  located in an upper position relative to the outer side walls  607 , a bed of powder is spread over the platform  605 . An energy beam (e.g., a laser, UV light, electron, etc.) is directed across the bed of powder causing the powder to fuse thereby forming a layer of the object. Then, the movable platform  605  is lowered slightly relative to the outer side walls  607  and another layer of powder is spread over the movable platform  605 . The beam is directed across the new layer of powder to form another layer of the object. The process is repeated to form the entire object. Depending on the sizes of the objects being printed, multiple objects can be printed in the exchangeable printing frame  606  at the same time. When the printing is finished, the movable platform  605  is at a bottom position in the exchangeable printing frame  606  and the entire formed solid objects are encased in unfused powder in the exchangeable printing frame  606 . 
     In the system  600  in  FIG.  9   , the exchangeable printing frame  606  from a 3D powder bed printer is fitted into the receiving area  604 . In this embodiment, the receiving area  604  includes a tray that can be slid outward from the receiving area  604  to receive therein the exchangeable printing frame  606 . After the exchangeable printing frame  606  is installed in the tray, the tray is slid back into the receiving area  604 . The exchangeable printing frame  606  contains the objects that were printed by the 3D printer as well as the unfused powder surrounding and encasing the objects. In this embodiment, the receiving area  604  has specific dimensions to accommodate an exchangeable printing frame from a specific 3D printer. In alternative embodiments, the receiving area  604  may have different dimensions to accommodate sizes of frames from different printers. Alternatively, the receiving area  604  may have adjustable dimensions that can be adjusted to accommodate different sizes of frames from different 3D printers. In one embodiment, a sealing member (not shown) engages the exchangeable printing frame  606  to provide an airtight seal around it. 
     Below the receiving area  604  is a cooling device  610 . In one embodiment, the cooling device  610  is a radiator that receives a circulating fluid, such as chilled water or water from a facility water supply. The cooling device  610  serves to reduce the temperature of the powder and objects in the exchangeable printing frame  606 , if necessary. In one embodiment, it is preferable that the powder and objects in the exchangeable printing frame  606  be below approximately 100° C. One or more temperature sensors (not shown) located in the receiving area  602  can be used to measure the temperature of the powder and objects in the exchangeable printing frame  606  in the receiving area  602 . 
     Adjacent to the receiving area  604  is a processing chamber  620  (or parts bin). Above the receiving area  604  and the processing chamber  620  is a transfer chamber  618 . The transfer chamber  618  extends horizontally over the receiving area  602  and the processing chamber  620 . A bottom wall of the transfer chamber  618  includes a first opening into the receiving area  602  and a second opening into the processing chamber  620 . 
     A lift mechanism  624  is located below the receiving area  604 . The lift mechanism  624  includes two components: an outer portion component  625  and an inner portion component  626 . An upper end  627  of the outer portion component  625  engages the outer walls  607  of the exchangeable printing frame  606  when the exchangeable printing frame  606  is in the receiving area  602 . An upper end  628  of the inner portion component  626  engages the movable platform  605  of the exchangeable printing frame  606  when the exchangeable printing frame  606  is in the receiving area  602 . The lift mechanism  624  is operable to elevate the exchangeable printing frame  606  toward the opening into the transfer chamber  618 . When an upper side of the exchangeable printing frame  606  is aligned and sealed with a bottom of the transfer chamber  620 , the outer portion component  625  ceases to elevate the outer walls  607  of the exchangeable printing frame  606  but the inner portion component  626  continues to elevate the movable platform  605  of the exchangeable printing frame  606  thereby causing all the powder in the exchangeable printing frame  606 , as well as the printed objects encased in the powder, to be pushed into the transfer chamber  618  through the opening in the bottom wall thereof. The transfer chamber  618  and the receiving area  604  are connected with an airtight seal to prevent or minimize the escape of powder when the lift mechanism  624  pushes the powder and objects from the exchangeable printing frame  606  into the transfer chamber  618 . 
     In the transfer chamber  618  is a movable decoating wall panel  632 . Before the lift mechanism  624  pushes the powder and objects into the transfer chamber  618 , the movable decoating wall panel  632  is located in the transfer chamber  618  at an end opposite the processing chamber  620 . The movable decoating wall panel  632  is operable to translate horizontally across the transfer chamber  618  to push the powder and objects encased therein received from the receiving area  604  horizontally through the transfer chamber  618  toward the opening in the bottom wall of the transfer chamber  618  into the processing chamber  620  so that the powder and objects encased therein drop into the processing chamber  620 . In one embodiment, a sealing member (not shown) engages the decoating wall panel  632  to provide an airtight seal around it. 
     An upper bellows  634  connects the transfer chamber  618  to the processing chamber  620 . The upper bellows  634  forms an airtight seal between the transfer chamber  618  and the processing chamber  620  yet allows for relative movement between the transfer chamber  618  and the processing chamber  620 . 
     The processing chamber  620  includes a processing platform  636 . The processing platform  636  is located approximately midway between a top and a bottom of the processing chamber  636 . The processing platform  636  has a structure that allows powder to pass through it but prevent objects from passing through it. Referring to  FIG.  11   , in this embodiment, the processing platform  636  is formed of a plurality of rods  640  that extend across the processing chamber  620 . Each of the rods  640  has a diameter of approximately 6.35 mm (¼ inch). The rods  640  are spaced from each other leaving a gap of approximately 3.17 mm (⅛ inch) between adjacent rods. The rods  640  are composed of a durable material, such as stainless steel. The rods  640  are affixed to the sides of the processing chamber  620 . 
     When the movable wall panel  632  pushes the powder and objects encased therein into the processing chamber  620 , the powder and objects encased therein fall onto the processing platform  636 . 
     Referring again to  FIG.  9   , located in a bottom floor  648  of the processing chamber  620  is an exit chute  652 . The bottom floor  648  of the processing chamber  620  is slanted downward towards the exit chute  652 . 
     Located below the exit chute  652  is a powder collection bin  656 . A lower bellows  660  connects the exit chute  652  to the powder collection bin  656 . The lower bellows  660  forms an airtight seal between the processing chamber  620  and the powder collection bin  656  yet allows for relative movement between the powder collection bin  656  and the processing chamber  620 . 
     The processing chamber  620  is supported from its bottom on a plurality of springs  664  (only one of which is shown). The springs  664  allow the processing chamber  620  to move or vibrate. In one embodiment the springs  664  allow the processing chamber  620  to move vertically up and down. 
     Connected to the bottom of the processing chamber  620  is a driver (or shaker)  670 . The driver  670  is a device that has an output shaft that oscillates up-and-down at selectable speeds, frequencies, and amplitudes. The connection of the driver  670  to the processing chamber  620  is fixed so that the driver  670  can cause the processing chamber  620  to move up and down at selectable speeds, frequencies, and amplitudes. A cooling device, such as a fan, (not shown) is associated with the driver  670  to reduce or prevent overheating. 
     The system  600  can be operated to receive an entire exchangeable printer frame containing 3D printed objects still encased in powder, automatically dispense the powder and objects encased from the exchangeable printer frame into the processing chamber whereupon the powder can be removed from the objects. The embodiment of the system  600  provides for recovery of much or all the unfused powder with minimal or no handling on the part of an operator. 
     Once the powder and objects encased in the powder (and optionally abrasive material) are located on the processing platform  636  in the processing chamber  620 , the driver  670  is operated to cause the entire processing chamber  620  to move (or oscillate or vibrate). As described in connection with other embodiments, the operating parameters, i.e., including frequency, amplitude, and duration of vibration, are selectable. Selection of appropriate operating parameters, including frequency, amplitude, and duration of vibration, is based on factors including efficient removal of powder, reducing damage to the objects, and amount of powder to be removed. Selection of an appropriate frequency, amplitude, and duration of vibration takes into account information and parameters about the powder and the objects encased in the powder, including the sizes of the objects, wall thicknesses of the objects, material composition of the objects, internal and external surfaces, and internal passages, as well as other factors. In one embodiment, information and parameters about the objects are obtained from the design file used by the 3D printer to produce the objects. In this embodiment, information and parameters about the objects in the design file are used to select appropriate operating parameters, including frequency, amplitude, and duration of vibration, to depowder the objects in the processing chamber  620 . One or more cycles, each with a different set of operating parameters, may be determined. Use of the design file information to select appropriate operating parameters for frequency, amplitude, and duration of vibration in the processing chamber  620  can be done automatically by software programming in the system  600 , or alternatively the use of the design file information to select appropriate operating parameters for frequency, amplitude, and duration of vibration in the processing chamber  620  can be done manually or by an operator or by reference to previously stored recipes or profiles. 
     In one embodiment, the processing chamber  620  is vibrated at a subsonic frequency. Other higher or lower frequencies may be used including sonic or ultrasonic. For example, the processing chamber  620  is vibrated at a frequency between 10-500 hertz. The amplitude of displacement of the processing chamber  620  when it is vibrated is related to the frequency and acceleration. In exemplary embodiments, the displacement can be approximately 0.75 inches (2 cm). 
     In one embodiment, operating parameters, including frequency, amplitude, and duration, are selected to impart more than 1 g acceleration to the processing chamber  620 . For example, operating parameters are selected to impart 2 g or more acceleration with a sinusoidal wave motion to the processing chamber  620 . When the processing chamber  620  is vibrated at greater than 1 g acceleration, objects and powder (which fall at 1 g) in the processing chamber  620  become suspended above the processing platform  636  when the processing chamber  620  is accelerating downward. When the processing chamber  620  reverses direction and begins to accelerate upward, impacts occur between the upward moving processing platform  636  and the powder or objects which are falling downward toward the processing platform  636 . These impacts can serve to shake the powder off of the objects. Likewise, if there are depowdered objects on the upward moving processing platform  636 , there are impacts between these depowdered objects and falling powder or objects above the depowdered objects on the processing platform  636 . These impacts can also serve to shake powder off of objects. 
     In one embodiment, the operating parameters (i.e., frequency, amplitude and duration of vibration) selected and applied to the processing chamber  620  are chosen to cause the objects encased in powder to vibrate in resonance. The objects encased in powder may have a resonant frequency that is different from the powder in which the objects are encased. When the processing chamber  620  is vibrated at a frequency that induces the objects to vibrate in resonance, the objects will vibrate (i.e., move) relative to the powder encasing them. This process can facilitate powder removal from the objects. This process can also facilitate powder removal from internal passages located inside the objects. 
     The amount of time required to depowder the objects in the printing frame can vary depending on the size of the objects, the geometries of the objects, temperature, and various other factors. For example, the duration of operation may range from approximately a minute to approximately an hour. 
     As the processing chamber  620  is vibrated, powder removed from the objects passes through the gaps between the rods  640  of the processing platform  636 , falls to the bottom of the processing chamber  620 , down the exit chute  652 , and collects in the powder collection bin  656 . The powder collection bin  656  is removable so that when the depowdering operation is finished, the entire powder collection bin  656 , filled with powder, can be removed. A fork lift or other appropriate lift mechanism may be used, if appropriate. The powder collected in the powder collection bin  656  can be recycled or otherwise appropriately disposed of 
     The system  600  includes a ventilation system (e.g., air circulation). The ventilation system is designed to reduce or eliminate air or powder from escaping from inside the housing  602 . The ventilation system maintains a pressure inside the housing lower than the air pressure outside the housing  602 . Located in the housing  602  directly adjacent the location of the cooling device  610  is an air inlet  680 , shown in  FIG.  10   . An air filter (not shown) is located directly behind the air inlet  680 . The system  600  includes first and second exhaust stacks  684  and  688  connected to and extending from the top of the housing  602 . One or more air filters (not shown) are located in line with each of the exhaust stacks  684  and  688 . The ventilation system includes one or more fans  682  (shown in  FIG.  9   ) associated with the exhaust stacks  684  and  688 . The fans  682  draw air into the housing  602  through the air inlet  680  and expel air from the housing  602  through the first and second exhaust stacks  684  and  688 . The doors and panels on the housing  602  are airtight and include airtight seals to reduce or prevent passage of air into or out of the housing except through the air inlet  680  and exhaust stacks  684  and  688 . 
     As shown in  FIG.  10   , the housing  602  includes a viewing window  690 . The viewing window  690  is located adjacent to the transfer chamber  618 . The viewing window  690  enables an operator to view the contents of the transfer chamber  618  as well as into the processing chamber  620 . A light fixture  692  (shown in  FIG.  9   ) is located in the transfer chamber  618  to help viewing the interior of the transfer chamber  618  and the processing chamber  620  through the viewing window  690 . 
     The system  600  includes one or more cameras  700  and  702  located inside the housing  602 . More specifically, the cameras  700  and  702  are located in the transfer chamber  618 . One of the cameras  700  is aimed toward the receiving area end of the transfer chamber  618 . The other camera  702  is aimed downward toward the processing chamber  620 . The outputs of the cameras  700  and  702  are provided to the control panel  601  where the video from the cameras can be viewed. The outputs of the cameras  700  and  702  are also stored as data files for later viewing and analysis. 
     The embodiment of the system  600  includes sound insulation material. The processing chamber  620  can be operated at audible frequencies. Sound insulation can be installed lining interior sides of the panels from which the housing  602  is formed to reduce noise levels outside the system  600  during operation. 
     The housing  602  and internal compartments and chambers, including the receiving area  604 , transfer chamber  618 , processing chamber  620 , and powder collection bin  656  are composed of durable, rigid, non-reactive materials such as steel, powder-coated steel, stainless steel, aluminum, or high-strength plastics. 
     The system  600  includes various sensors used to monitor operation of the system and to provide that the system and its components are operating properly. An accelerometer is associated with the driver  670  and another accelerometer is associated with the processing chamber  620  to measure and detect movement of these components. One or more temperature sensors (e.g., thermocouples, infrared sensors, etc.) are associated with the transfer chamber  618 , the cooling device  610 , the driver  670 , and the powder collection bin  656 . Sound sensors are located inside and/or outside the housing  602  to detect noise levels. Pressure differential sensors are located on upstream and downstream sides of the filters, for example to detect clogging. Motion or displacement sensors are associated with the door panels to detect closure status. One or more particle sensors may be located inside the housing  602  to detect for possible leakage of powder from the processing chamber  620 . The system  600  may include other sensors in addition to those mentioned above. The sensors provide their outputs to the controller of the system  600 . 
     The system  600  includes several advantages. 
     One advantage of the system  600  is provided by the processing platform  636 . As described above and shown in  FIG.  11   , the processing platform  636  is formed of a plurality of rods  640  that extend across the processing chamber  620 . The processing platform  636  allows powder shaken off the objects to pass through gaps between the rods  640  and fall to the bottom of the processing chamber  620  while preventing the objects being depowdered from passing through. The rods  640  present relatively low friction horizontally thereby allowing objects to move horizontally along the rods  640  across the processing platform  636 . 
     Providing gaps that allow objects to move horizontally along the processing platform  636  is preferable to providing a grid of small openings because an object may become stuck in a small opening thereby clogging the opening and possibly damaging the object. However, by using rods with gaps between them, objects are able to slide horizontally thereby not clogging the gaps and reducing the possibility of damage to the objects. 
     Another advantage of the embodiment of the system  600  in  FIGS.  9  and  10    is that it can handle large outputs from a powder bed 3D printer. The system  600  is capable of removing the powder from all the objects in an entire exchangeable printing frame at one time in a single operation. Such a frame can weigh up to approximately 90 kg (200 pounds). 
     Another advantage of the system  600  in  FIGS.  9  and  10    is that it reduces handling of the objects from the 3D printer. With the system  600 , the entire printing frame containing the objects and the unfused powder is installed in the receiving area without the need for an operator to remove the powder and objects from the printing frame. Removal of the powder and objects takes place internally in the housing of the system  600  thereby reducing the amount of powder escaping and increasing the amount of powder that can be recovered or recycled. 
     Other Alternatives 
     In one of the embodiments disclosed above, it was described that a solid abrasive media was placed with the parts to be cleaned or finished on the vibratory platform. In an alternative embodiment, the parts can be cleaned or finished without adding a solid abrasive media. In this alternative, the parts to be cleaned or finished are placed on the vibratory platform, which is vibrated for a period of time. This alternative may be suitable for some types of parts, such as particularly delicate parts. 
     In an embodiment described above, the system operates without application of other material removal technologies. In alternative embodiments, a system using a vibratory platform for removal of unwanted material may also use other technologies to supplement, augment or complement unwanted material removal. Such other technologies may include application of acoustic energy, pressurized sprays (liquid, solids, or gaseous) or application of chemicals, such as detergents. These other technologies may be incorporated into the same system or chamber that includes the vibratory platform or may be located in another chamber located adjacent to or in-line with the chamber that includes the vibratory platform. 
     In the embodiments in  FIGS.  2 ,  5 ,  7 A and  7 B , the vibratory platform is solid. In an alternative embodiment, the vibratory platform includes openings so that any unwanted material detaching from the parts will fall through the openings to the bottom of the chamber. The openings may be of any suitable size or type, including without limitation a mesh construction. Instead of openings, the platform may be made of other constructions that allow material detaching from the parts to fall to the bottom of the chamber. 
     In embodiments disclosed above, the removal of unwanted material from an additively manufactured object can be conducted at room temperature. In alternative embodiments, heat may be applied in conjunction with a vibratory platform to facilitate removal of unwanted material from additively manufactured parts. To apply heat to facilitate removal of unwanted material from additively manufactured parts, a heating element may be included in the chamber of the system. The heater may be operated under control of the control unit. Alternatively, a heater may be operated based on input provided by a user through the user interface. In still further alternative embodiments, the system may include a cooling element to cool or refrigerate the air in the chamber during the material removal process. The cooling element may be operated under control of the control unit based on information contained in a profile or may be operated based on input provided by a user through the user interface. In further alternatives the system may include both a heating element and a cooling element. 
     In various different embodiments, different kinds of vibrations, different kinds of waveforms, different frequencies of waves, and different amplitudes of waves may be applied to the vibratory platform. Different kinds of waveforms include sine waves, square waves, sawtooth waves, as well as others. In some alternatives, multiple different vibrations, multiple different waveforms, multiple different amplitudes, multiple different frequencies of waves, or combinations thereof, may be applied at the same time to parts in the chamber. When applying different vibrations, waveforms, amplitudes or frequencies, the different vibrations, waveforms, amplitudes or frequencies may be applied from the same vibratory platform. The frequency being applied to the vibratory platform may be in the audible range, the ultrasonic range, or any other range. 
     In some of the embodiments described above, the interior of the chamber is maintained at atmospheric pressure. In other alternatives, the chamber may be maintained at a pressure that is higher or lower than atmospheric pressure, including near vacuum pressures. Alternatively, the pressure in the interior of the chamber may be changed during the material removal process. The pressure changes and the timing of the changes may be specified in the profile. 
     In the embodiments described above, an operating profile was selected by the user. In another alternative, the user may specify some or all the operating parameters manually. In another alternative, the operating parameters may be specified by the entity that performed the 3D printing portion of the additive manufacturing process. 
     In another alternative, the system automatically measures the progress of unwanted material removal while the material is being removed, and automatically auto-adjusts the operating parameters to improve or complete the removal process. This alternative may employ the AUTOMAT3D® technology developed by PostProcess Technologies, Inc. An embodiment of this technology is disclosed in copending patent application US20190315065, the entire disclosure of which is incorporated by reference herein. Sensors in the chamber measure the progress of the material removal process and feedback this information to a digital file that is used to modify or adjust the operating parameters. 
     In still another alternative, the unwanted material removal system is part of an overall additive manufacturing system that includes the object formation portion as well as the unwanted material removal portion. According to this alternative, the design file for object formation (e.g., a CAD file) and the operating profiles for material removal are part of an overall design file that both forms the object and removes unwanted material. In such an alternative, object formation and unwanted material removal are designed together for overall optimization and efficiency of object manufacturing. One alternative is the CONNECT3D® technology developed by PostProcess Technologies, Inc. An embodiment of this technology disclosed in copending patent application US20190275745, the entire disclosure of which is incorporated by reference herein. In some automated embodiments, the material removal process may be performed without user input or in a closed loop. Further, in some embodiments of an overall additive manufacturing system, the object may be moved on a conveyor, by robotic arm, or other means from the location where the object is formed to another location where vibratory energy is applied to remove unwanted material. In still other embodiments, vibratory energy is applied to remove unwanted material from an additively manufactured object in the same location (e.g., chamber) where the object is formed. 
     In some of the embodiments, the interior walls of the chamber are anechoic, or otherwise adapted so as to enhance or not detract from delivery of energy to the object(s) and material on the platform. 
     Different frequencies can be applied to the vibratory platform. In one embodiment, a frequency of between 75 and 135 Hertz is used. In another alternative, a frequency of between 35-135 Hertz is used. In yet another alternative, a frequency of between 10-500 hertz is used. Other frequencies may be suitable. The platform may vibrate continuously or intermittently, for example to facilitate powder removal. Movement of the platform may be specified in the operating profile. 
     In embodiments described above, the medium inside the chamber is air. In alternative embodiments, other fluid media either gaseous or liquid may be used inside the chamber. 
     In another alternative embodiment, the platform rotates, i.e., a rotating turntable. 
     Advantages 
     The disclosed embodiments have several advantages. One advantage is that the unwanted material can be readily recycled. Compared to material removal systems that use a liquid spray, the disclosed embodiments provide for relatively easier recovery of removed material for recycling. Compared to material removal systems that use a liquid spray, the disclosed embodiments do not require filtering of the liquid after spraying for reuse, recovery or recycling of the liquid and/or recycling of the removed material. Compared to material removal systems that use application of chemicals, the disclosed embodiments have the advantage that the unwanted material is removed from additively manufactured objects without having the objects come in contact with any chemicals. 
     Furthermore, compared to material removal systems that use application of chemicals, the disclosed embodiments avoid the costs (including disposal costs) of such chemicals. 
     The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter. 
     It is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is understood that the following claims including all equivalents are intended to define the scope of the disclosure. The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the disclosure.