Sinterable separation material in additive manufacturing

Patent metadata

Field	Value
Publication number	US-2021197493-A1
Application number	US-202017060916-A
Country	US
Kind code	A1
Filing date	Oct 1, 2020
Priority date	Dec 2, 2016
Publication date	Jul 1, 2021
Grant date	—

Abstract

According to one aspect, embodiments of the invention provide a method of 3D printing, comprising depositing a model material in successive layers to form a part, the model material being a metal composite including greater than 50% by volume metal powder and less than 50% by volume a first removable binder, depositing the model material in successive layers to form a support structure adjacent the part, depositing a sinterable separation material between a surface of the part and a surface of the support structure, the sinterable separation material formed from 10-40% by volume ceramic powder and greater than 50% by volume a second removable binder, debinding the first removable binder of the model material and the second removable binder of the sinterable separation material, and sintering the part, the support structure, and the sinterable separation material at a temperature profile that sinters the model material and the sinterable separation material.

First claim

What is claimed is:

1 - 28 . (canceled)

29 . A method of additively manufacturing an object, the method comprising:
depositing a composite including a metal particulate filler and a debindable matrix in successive layers to form a densification linking platform, densification linking supports, and a densification linking part, at least a portion of the successive layers of the object having at least one wall substantially enclosing an interior volume of a part; forming a debinding acceleration structure having interconnected chambers and a plurality of access channels that penetrate one or more of the at least one wall exposing the composite, such that when exposed to a fluid debinder during a debinding process, the exposed composite forms a brown part including the debound densification linking platform, the debound densification linking supports, and the debound densification linking part; debinding the composite including penetrating the fluid debinder into the debinding acceleration structure through the plurality of access channels to debind the matrix from within the interior volume of the densification linking platform, the densification linking supports, or the part; and sintering, during a sintering process, the brown part assembly to densify at a rate substantially common throughout the brown part assembly to form the object.

30 . The method of claim 29 , further comprising connecting a portion of the plurality of access channels to a pressurized supply of debinding fluid to force debinding fluid through the portion of the plurality of access channels.

31 . The method of claim 29 , wherein the step of forming the interconnected chambers and the plurality of access channels that penetrate the one or more of the at least one wall exposing the composite of the debinding acceleration structure comprises fluidly interconnecting a plurality of honeycomb cavities.

32 . The method of claim 29 , further comprising forming the debinding acceleration structure in additive layers, wherein at least one of the plurality of access channels spans a plurality of the additive layers.

33 . The method of claim 29 , further comprising:
depositing one or more part release layers between the densification linking supports and the part with a release composite comprising a ceramic particulate filler and a binder; and forming a routing channel through the part release layer and to at least one of the plurality of access channels that permits the fluid debinder to flow through the one or more part release layers to the densification linking supports.

34 . The method of claim 29 , wherein the step of debinding comprises cyclically filling and draining the debinding acceleration structure using a fluid debinder, thereby repeatedly immersing the densification linking platform, the densification linking supports, and the part, as well as filling and draining the interconnected chambers, to form the brown part assembly.

35 . The method of claim 29 , wherein the step of debinding comprises holding the densification linking platform, the densification linking supports, and the part immersed in the debinding chamber for a dwell time that permits the fluid debinder to flow through the plurality of access channels.

36 . The method of claim 29 , wherein the step of debinding comprises penetrating the fluid debinder throughout the interconnected chambers to debind the matrix from within the interconnected chambers.

37 . The method of claim 29 , wherein interconnections between the interconnected chambers have a cross sectional area of less than 1% of a surface area of the interior volume of the densification linking platform, the densification linking supports, or the part.

38 . The method of claim 29 , wherein depositing the composite in successive layers to form the debinding acceleration structure comprises depositing the composite within the interior volume of the densification linking supports connected to lateral sides of the part.

39 . A method of additively manufacturing an object, the method comprising:
receiving, by a controller, a first tool path for a first layer of a part, wherein the received first tool path comprises a perimeter contour segment in the first layer; receiving, by the controller, a second tool path for a second layer of the part, wherein the received second tool path comprises a parallel segment adjacent to the perimeter contour segment; depositing a composite comprising a polymer-based matrix and a powdered sinterable metal in a pattern that follows the perimeter contour segment of the received first tool path to produce a perimeter path of the composite; depositing the composite in a pattern that follows the parallel segment of the received second tool path in a retrograde direction with respect to the perimeter path to produce a stress-offsetting adjacent path of the composite, depositing the composite in a pattern that follows the parallel segment of the received second tool path to produce a stress-offsetting retrograde adjacent path of the composite, wherein the perimeter path and the stress-offsetting adjacent path are deposited in retrograde directions with respect to one another such that directions of residual stress within the polymer-based binder of the composite are opposite in the perimeter path and the stress-offsetting retrograde adjacent path.

40 . The method of claim 39 , wherein stresses within the stress-offsetting adjacent path are continuously adjacent to, parallel to, and opposite to at least 90 percent of stresses within the perimeter path.

41 . The method of claim 39 , further comprising debinding the polymer-based matrix sufficient to form a shape-retaining brown part.

42 . The method of claim 41 , further comprising sintering the shape-retaining brown part to densify the part as neighboring metal particles throughout the shape-retaining brown part undergo atomic diffusion, wherein the deposition of the composite positions residual stresses within the polymer-based binder in opposing directions in the perimeter path and the stress-offsetting adjacent path and reduces part twist caused by stress and relaxation of polymer chains in the composite.

43 . The method of claim 39 , wherein the second tool path is continuously adjacent to and parallel to at least 90 percent of a length of the first tool path within an adjacent layer.

44 . The method of claim 39 , further comprising depositing the composite in a pattern along a direction changing tool path segment, wherein the direction changing tool path segment is a reflex angle continuation joining the first tool path and the second tool path within a same layer.

45 . The method of claim 39 , further comprising depositing the composite to form sintering supports below the part.

46 . The method of claim 39 , further comprising forming one or more release layers of a release composite including a ceramic particulate filler and a binder between the part and the sintering supports.

47 . The method of claim 39 , wherein the step of debinding the polymer-based matrix sufficient to form the shape-retaining brown part comprises debinding the polymer-based matrix of the part and the sintering supports.

48 . The method of claim 46 , further comprising debinding the binder of the one or more release layers, thereby allowing a ceramic particulate that facilitates release of the part from the sintering supports to remain; and
sintering, during a sintering process, the part and the sintering supports t

Assignees

• Markforged Inc

Inventors

• Mark Gregory Thomas
• Woodruff Rick Bryan
• Chao Michelle Ling

Classifications

• B29C64/40 Primary

  Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof · CPC title

• B29C64/165 Primary

  using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber · CPC title

• B22F10/50

  Treatment of workpieces or articles during build-up, e.g. treatments applied to fused layers during build-up · CPC title

• B22F10/47

  characterised by structural features · CPC title

• B22F10/32

  of the atmosphere, e.g. composition or pressure in a building chamber · CPC title