SINTERING ADDITIVELY MANUFACTURED PARTS WITH A DENSIFICATION LINKING PLATFORM
To reduce distortion in an additively manufactured part, a densification linking platform and/or supports of the same composite as the desired part may be printed below the part. After debinding, a resulting shape-retaining brown part assembly is sintered to densify together at a same rate as neighboring metal particles throughout the shape-retaining brown part assembly undergo atomic diffusion. Distortion is reduced by interconnecting portions of the shape-retaining brown part assembly, printing release layers among the portions, depositing adjacent roads of the assembly in retrograde directions, and/or providing channels to accelerate a debinding process.
1 . A method of reducing distortion in an additively manufactured part; comprising:
forming a densification linking platform of successive layers of composite, the composite including a metal particulate filler in a polymer-based binder matrix;
forming densification linking supports of successive layers of the composite above the densification linking platform;
forming a desired part of successive layers of the composite upon the densification linking platform and densification linking supports;
depositing the composite along tool paths, wherein adjacent tool paths are deposited in retrograde directions during the forming of the densification linking platform, the densification linking supports, and the desired part,
debinding the binder matrix sufficient to form a shape-retaining brown part assembly including the densification linking platform, the densification linking supports, and the desired part; and
sintering the shape-retaining brown part assembly formed from the composite to densify the densification linking platform, the densification linking supports, and the desired part together at a same rate as neighboring metal particles throughout the shape-retaining brown part assembly undergo atomic diffusion, wherein the deposition of the composite in adjacent toolpaths in retrograde directions reduces part twist caused by stress and relaxation of polymer chains in the adjacent toolpaths.
2 . The method according to claim 1 , further comprising:
forming the densification linking platform, the densification linking supports, and the desired part to substantially align a centroid of the combined densification linking platform and connected densification linking supports with a centroid of the desired part.
3 . The method according to claim 1 , further comprising:
interconnecting the densification linking supports to a side of the desired part by forming separable attachment protrusions of the composite between the densification linking supports and the side of the desired part.
4 . The method according to claim 1 , further comprising:
forming a lateral densification linking shell of the composite following a portion of a lateral contour of the desired part;
connecting the lateral densification linking shell to the densification linking platform; and
connecting the lateral densification linking shell to the portion of the lateral contour of the desired part by forming separable attachment protrusions of the composite between the lateral densification linking shell and the desired part.
5 . The method according to claim 1 , further comprising:
forming soluble support structures of a soluble material;
before sintering the shape-retaining brown part assembly, debinding the matrix sufficient to form a shape-retaining brown part assembly including the densification linking platform, the densification linking supports, and the desired part, and debinding the soluble material of the soluble support structures.
6 . The method according to claim 1 , further comprising:
forming part release layers between the densification linking supports and the desired part with a release composite including a ceramic particulate filler and the debindable matrix;
keeping the part release layers and the shape-retaining brown part assembly together as a unit during the debinding and during the sintering; and
after sintering, separating the part release layers, the densification linking platform, and the densification linking supports from the desired part.
7 . The method according to claim 1 , further comprising adjusting one of a start of depositing the composite along the tool paths and a stop of depositing the composite along the tool paths to be located within an interior region of a layer of the desired part.
8 . The method according to claim 7 , wherein a contour tool path between the start point and the stop point further defines a raster path that at least partially fills the interior region.
9 . The method according to claim 1 , wherein the adjacent tool paths are within a same layer.
10 . The method according to claim 1 , wherein the adjacent tool paths are within adjacent layers.
11 . A method of reducing distortion in an additively manufactured part; comprising:
forming a densification linking platform of successive layers of composite, the composite including a metal particulate filler in a polymer-based binder matrix;
forming densification linking supports of successive layers of the composite above the densification linking platform;
forming a desired part of successive layers of the composite upon the densification linking platform and densification linking supports;
depositing the composite along wall tool paths and along infill tool paths within the wall tool paths during the forming of the densification linking platform, the densification linking supports, and the desired part, at least a portion of the wall tool paths forming a plurality of access channels penetrating within the wall tool paths;
debinding the binder matrix, by flowing a debinding fluid around the densification linking platform, the densification linking supports, and the desired part and through the plurality of access channels, sufficient to form a shape-retaining brown part assembly including the debound densification linking platform, the densification linking supports, and the desired part; and
sintering the shape-retaining brown part assembly formed from the composite to densify the densification linking platform, the densification linking supports, and the desired part together at a same rate as neighboring metal particles throughout the shape-retaining brown part assembly undergo atomic diffusion.
12 . The method according to claim 11 , further comprising:
interconnecting the densification linking supports to a side of the desired part by forming separable attachment protrusions of the composite between the densification linking supports and the side of the desired part.
13 . The method according to claim 11 , further comprising:
forming a lateral densification linking shell of the composite following a lateral contour of the desired part;
connecting the lateral densification linking shell to the densification linking platform; and
connecting the lateral densification linking shell to the lateral contour of the desired part by forming separable attachment protrusions of the composite between the lateral densification linking shell and the desired part.
14 . The method according to claim 11 , further comprising:
forming soluble support structures of a soluble material, the soluble support structures resisting downward forces during the forming of the desired part;
before sintering the shape-retaining brown part assembly, debinding the matrix sufficient to form a shape-retaining brown part assembly including the densification linking platform, the densification linking supports, and the desired part and debinding the binder of the soluble support structures.
15 . The method according to claim 11 , further comprising:
forming part release layers between the densification linking supports and the desired part with a release composite including a ceramic particulate filler and a binder;
keeping the part release layers and shape-retaining brown part assembly together as a unit during the debinding and during the sintering; and
after sintering, separating the part release layers, the densification linking platform, and the densification linking supports from the desired part.
16 . The method according to claim 11 , wherein at least a portion of the infill tool paths forms a plurality of distribution channels among the infill tool paths, and wherein the method further comprises:
flowing the debinding fluid through the plurality of access channels and through the plurality of distribution channels to accelerate the debinding.
17 . The method according to claim 11 , wherein at least a portion of the infill tool paths forms a plurality of distribution channels fluidly interconnecting to a pair of access channels, and wherein the method further comprises flowing the debinding fluid through one of the pair of access channels, through the plurality of distribution channels, and out through the remaining one of the pair of access channels to accelerate the debinding.
18 . The method according to claim 11 , further comprising draining and replenishing a bath of the debinding fluid surrounding the densification linking platform, the densification linking supports, and the desired part to accelerate the debinding.
19 . The method according to claim 11 , further comprising draining and replenishing a supply of the debinding fluid entering the access channels to accelerate fluid flow through the access channels and accelerate the debinding.
20 . A method of reducing distortion in an additively manufactured part; comprising:
forming a densification linking platform of successive layers of composite, the composite including a metal particulate filler in a polymer-based binder matrix;
forming a desired part of successive layers of the composite upon the densification linking platform and densification linking supports;
depositing the composite along tool paths, wherein adjacent tool paths are deposited in retrograde directions during the forming of the densification linking platform and the desired part and at least a portion of the tool paths form channels penetrating the tool paths;
debinding the binder matrix sufficient to form a shape-retaining brown part assembly including the densification linking platform, the densification linking supports, and the desired part, wherein the channels penetrating the tool paths accelerate debinding; and
sintering the shape-retaining brown part assembly formed from the composite to densify the densification linking platform, the densification linking supports, and the desired part together at a same rate as neighboring metal particles throughout the shape-retaining brown part assembly undergo atomic diffusion, wherein the deposition of the composite in adjacent toolpaths in retrograde directions reduces part twist caused by stress and relaxation of polymer chains in the adjacent toolpaths.
21 . The method according to claim 20 , further comprising:
interconnecting the densification linking platform to a bottom of the desired part by forming separable attachment protrusions of the composite between the densification linking platform and the bottom of the desired part.
22 . The method according to claim 20 , further comprising:
forming soluble structures of a soluble material between the densification linking platform and the desired part; and
before sintering the shape-retaining brown part assembly, debinding the matrix sufficient to form a shape-retaining brown part assembly including the densification linking platform and the desired part, and debinding the soluble material of the soluble structures.
23 . The method according to claim 20 , further comprising:
forming densification linking supports of successive layers of the composite above the densification linking platform;
forming part release layers between the densification linking supports and the desired part with a release composite including a ceramic particulate filler and a binder;
keeping the part release layers and shape-retaining brown part assembly together as a unit during the debinding and during the sintering; and
after sintering, separating the part release layers, the densification linking platform, and the densification linking supports from the desired part.
24 . The method according to claim 20 , wherein the adjacent tool paths are within a same layer.
25 . The method according to claim 20 , wherein the adjacent tool paths are within adjacent layers.
26 . The method according to claim 20 , further comprising:
depositing the composite along wall tool paths and along infill tool paths within the wall tool path, at least a portion of the wall tool paths forming channels penetrating the wall tool paths;
flowing the debinding fluid in and out through the channels penetrating the wall tool paths.
27 . The method according to claim 20 , further comprising draining and replenishing a supply of the debinding fluid entering the channels to accelerate fluid flow through the channels and accelerate the debinding.
28 . The method according to claim 20 , further comprising draining and replenishing a bath of the debinding fluid surrounding the densification linking platform and the desired part to accelerate the debinding.