Supports for sintering additively manufactured parts

Patent metadata

Field	Value
Publication number	US-10000011-B1
Application number	US-201715722445-A
Country	US
Kind code	B1
Filing date	Oct 2, 2017
Priority date	Dec 2, 2016
Publication date	Jun 19, 2018
Grant date	Jun 19, 2018

Abstract

To reduce distortion in an additively manufactured part, a shrinking platform is formed from a metal particulate filler in a debindable matrix. Shrinking supports of the same material are formed above the shrinking platform, and a desired part of the same material is formed upon them. A sliding release layer is provided below the shrinking platform of equal or larger surface area than a bottom of the shrinking platform to lateral resistance between the shrinking platform and an underlying surface. The matrix is debound sufficient to form a shape-retaining brown part assembly including the shrinking platform, shrinking supports, and the desired part. The shape-retaining brown part assembly is heated to shrink all of the components together at a same rate via atomic diffusion.

First claim

What is claimed is:

1. A method of reducing distortion in an additively manufactured part; comprising:
forming a shrinking platform of successive layers of composite, the composite including a metal particulate filler in a debindable matrix;
forming shrinking supports of the composite above the shrinking platform;
forming a desired part of the composite upon the shrinking platform and shrinking supports, all portions of the desired part being vertically and directly supported by the shrinking platform;
forming a sliding release layer below the shrinking platform of equal or larger surface area than a bottom of the shrinking platform that reduces lateral resistance between the shrinking platform and an underlying surface;
debinding the matrix sufficient to form a shape-retaining brown part assembly including the shrinking platform, the shrinking supports, and the desired part; and
heating the shape-retaining brown part assembly formed from the composite to shrink all of the shrinking platform, the shrinking supports, and the desired part together at a same rate as neighboring metal particles throughout the shape-retaining brown part assembly undergo mass diffusion.

2. The method according to claim 1 , further comprising:
depositing an open cell structure including interconnections among cell chambers in at least one of the shrinking platform, the shrinking supports, and the desired part; and
penetrating a fluid debinder into the open cell structure to debind the matrix from within the open cell structure.

3. The method according to claim 1 , further comprising:
forming the shrinking platform, the shrinking supports, and the desired part to substantially align a centroid of the combined shrinking platform and connected shrinking supports with the centroid of the part.

4. The method according to claim 1 , further comprising:
interconnecting the shrinking supports to a side of the desired part by forming separable attachment protrusions of the composite between the shrinking supports and the side of the desired part.

5. The method according to claim 1 , further comprising:
forming a lateral support shell of the composite following a lateral contour of the desired part; and
connecting the lateral support shell to the lateral contour of the desired part by forming separable attachment protrusions of the composite between the lateral support shell and the desired part.

6. The method according to claim 1 , further comprising:
forming soluble support structures of the debindable matrix without the metal particulate filler that resist downward forces during the forming of the desired part; and
debinding the matrix sufficient to dissolve the soluble support structures before heating the shape-retaining brown part assembly.

7. The method according to claim 1 , further comprising:
forming soluble support structures of a release composite, the release composite including a ceramic particulate filler, the debindable matrix and less than a sinterable amount of the metal particulate filler, the soluble support structures resisting downward forces during the forming of the desired part; and
before heating the shape-retaining brown part assembly, debinding the matrix sufficient to form a shape-retaining brown part assembly including the shrinking platform, shrinking supports, and desired part and to dissolve the matrix of the soluble support structures.

8. The method according to claim 1 , wherein the underlying surface comprises a portable build plate, and wherein the method further comprises:
forming the shrinking platform above the portable build plate;
forming the sliding release layer below the shrinking platform and above the portable build plate with a release composite including a ceramic particulate and the debindable matrix;
sintering the shape-retaining brown part assembly during the heating;
keeping the build plate, sliding release layer, and shape-retaining brown part assembly together as a unit during the debinding and during the sintering;
after sintering, separating the build plate, sliding release layer, shrinking platform, and shrinking supports from the desired part.

9. The method according to claim 1 , further comprising:
forming part release layers between the shrinking supports and the desired part with a release composite including a ceramic particulate filler and the debindable matrix;
sintering the shape-retaining brown part assembly during the heating;
keeping the part release layers and shape-retaining brown part assembly together as a unit during the debinding and during the sintering;
after sintering, separating the part release layers, shrinking platform, and shrinking supports from the desired part.

10. The method according to claim 9 , further comprising:
depositing an open cell structure including interconnections among cell chambers in the shrinking supports; and
penetrating a fluid debinder into the open cell structure to debind the matrix from within the open cell structure.

11. A method of reducing distortion in an additively manufactured part; comprising:
depositing, in successive layers, a shrinking platform formed from a composite, the composite including a metal particulate filler in a debindable matrix;
depositing shrinking supports of the composite above the shrinking platform;
depositing an open cell structure including interconnections among cell chambers in the shrinking supports;
depositing, from the composite, a desired part upon the shrinking platform and shrinking supports;
exposing the shrinking platform, shrinking supports, and desired part to a fluid debinder to form a shape-retaining brown part assembly;
penetrating the fluid debinder into the open cell structure to debind the matrix from within the open cell structure; and
sintering the shape-retaining brown part assembly to shrink at a rate common throughout the shape-retaining brown part assembly.

12. The method according to claim 11 , further comprising:
depositing a sliding release layer below the shrinking platform of equal or larger surface area than a bottom of the shrinking platform that reduces lateral resistance between the shrinking platform and an underlying surface.

13. The method according to claim 11 , further comprising:
depositing part release layers between the shrinking supports and the desired part with a release composite including a ceramic particulate filler and the debindable matrix;
keeping the part release layers and shape-retaining brown part assembly together as a unit during the exposing and during the sintering;
after sintering, separating the part release layers, shrinking platform, and shrinking supports from the desired part.

14. The method according to claim 13 , further comprising:
forming vertical gaps without release composite between shrinking supports and the desired part where a vertical surface of a shrinking support opposes an adjacent wall of the desired part.

15. The method according to claim 11 , further comprising:
depositing a lateral support shell block having a large cell interior, having cells with cell cavities wider than a thickest wall within the lateral support shell block, to assist in diffusing and penetrating debinding fluid into the support.

16. The method according to claim 11 , further comprising:
interconnecting the shrinking supports to a side of the desired part by forming separable attachment protrusions of the composite between the shrinking supports and the side of the desired part.

17. The method according to claim 11 , further comprising:
forming a lateral

Assignees

• Markforged Inc

Inventors

• Mark Gregory Thomas

Classifications

• B29C64/40 Primary

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

• B22F10/47

  characterised by structural features · CPC title

• B22F3/1118

  comprising internal reinforcements · CPC title

• B29C64/209

  Heads; Nozzles · CPC title

• B29C64/165

  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