ADDITIVELY MANUFACTURED PARTS WITH DEBINDING ACCELERATION

1 . A method of depositing material for additive manufacturing, comprising:

feeding a composite material including a binder matrix and a sinterable powder;

depositing the composite material as an outer wall of a part;

depositing the composite material as infill within the outer wall of the part;

depositing the composite material to form a first access channel extending through the outer wall of the part to an interior volume formed by the infill;

depositing layers of honeycomb infill to form a distribution channel connecting an interior volume of the honeycomb infill to the first access channel; and

flowing a debinding fluid about the outer wall of the part and through the first access channel to the interior volume of the honeycomb infill to debind the part.

2 . The method according to claim 1 , further comprising:

depositing successive layers of the wall of the part to form a second access channel extending from the exterior of the part to an interior of the part; and

debinding the binder matrix by flowing a debinding fluid in through the first access channel, via the distribution channel, and out through the second access channel.

3 . The method according to claim 2 , further comprising:

connecting the first access channel to a pressurized supply of debinding fluid to force debinding fluid through the first access channel, distribution channel, and second access channel.

4 . A method of reducing distortion in an additively manufactured part, comprising:

depositing a densification linking platform formed from a composite, the composite including a metal particulate filler in a debindable matrix;

depositing densification linking supports of the composite and above the densification linking platform;

depositing a desired part of the composite upon the densification linking platform and adjacent the densification linking supports;

depositing a first debinding acceleration structure within at least one of the densification linking platform, the densification linking supports, and the desired part, the debinding acceleration structure including a shell wall, a plurality of infill walls within the shell wall forming honeycomb cavities, and an access channel through the shell wall to a honeycomb cavity adjacent the access channel,

exposing the densification linking platform, the densification linking supports, and the desired part to a fluid debinder to form a brown part assembly;

penetrating the fluid debinder into the first debinding acceleration structure through the access channel to debind the matrix from within the honeycomb cavities; and

sintering the brown part assembly to densify at a rate substantially common throughout the brown part assembly.

5 . The method according to claim 4 , further comprising:

depositing distribution channels in the first debinding acceleration structure fluidly interconnecting a plurality of the honeycomb cavities; and

penetrating the fluid debinder throughout the distribution channels to debind the matrix from within the fluidly interconnected honeycomb cavities.

6 . The method according to claim 4 , further comprising:

depositing the first debinding acceleration structure to form distribution channels of cross sectional area of less than 1% of a surface area of the infill walls.

7 . The method according to claim 4 , wherein the first debinding acceleration structure is deposited within the densification linking supports, and the access channel fluidly interconnects an exterior of the densification linking supports to an interior of the densification linking supports.

8 . The method according to claim 4 , wherein the first debinding acceleration structure comprises:

a through-hole wall forming a portion of the shell wall surrounding a through-hole through the at least one of the densifying platform, the densifying supports, and the desired part, the access channel being formed in the through-hole wall.

9 . The method according to claim 4 , wherein the first debinding acceleration structure includes a connection interface formed into the access channel, and wherein the method further comprises:

connecting a pressurized debinding fluid supply to the connection interface, and

forcing debinding fluid through the connection interface into the access channel.

10 . The method according to claim 4 , wherein the densification linking platform includes a routing channel interconnected to the access channel, and wherein the method further comprises:

flowing debinding fluid through the routing channel into the access channel.

11 . The method according to claim 4 , wherein the first debinding acceleration structure is deposited within densification linking supports connected to lateral sides of the desired part.

12 . The method according to claim 4 , further comprising:

depositing the first debinding acceleration structure in additive layers, wherein the access channel spans a plurality of the additive layers.

13 . The method according to claim 4 , further comprising:

depositing part release layers between the densification linking supports and the desired part with a release composite including a ceramic particulate filler and a binder; and

depositing a routing channel through the part release layer and to the access channel that permits debinding fluid flow through the part release layer to the densification linking supports.

14 . The method according to claim 4 , further comprising:

depositing distribution channels in the first debinding acceleration structure fluidly penetrating a plurality of the infill walls; and

supplying debinding fluid adjacent the first debinding acceleration structure to debind the matrix in the infill walls.

15 . The method according to claim 4 , further comprising:

locating the densification linking platform, the densification linking supports, and the desired part in a debinding chamber; and

cyclically filling and draining the debinding chamber using a fluid debinder, thereby repeatedly immersing the densification linking platform, the densification linking supports, and the desired part, as well as filling and draining the internal debinding cavities, to form the brown part assembly.

16 . The method according to claim 15 , further comprising;

holding the densification linking platform, the densification linking supports, and the desired part immersed in the debinding chamber for a dwell time that permits the fluid debinder to flow through the access channels.

17 . The method according to claim 15 , wherein the densification linking platform includes a plurality routing channels therethrough, and wherein the method further comprises:

flowing debinding fluid through the plurality of routing channels during the filling and draining.

18 . A method of depositing material for additive manufacturing, comprising:

feeding a composite including a polymer-based binder and a sinterable powder;

depositing walls of the composite by moving the deposition head to deposit the composite along adjacent and retrograde tool paths in retrograde directions;

depositing the walls to form an outer wall and an infill wall of a part;

depositing the walls to form an outer wall and an infill wall of a sintering support that supports the part versus gravity;

depositing the walls to form a first channel penetrating the outer wall of one of the part and the sintering support;

flowing a debinding fluid about the outer wall of the part and the outer wall of the sintering support and through the first channel to contact the inner wall of one of the wall or the sintering support;

sintering the part to densify the part and the sintering support, wherein the deposition of the composite along adjacent and retrograde paths positions residual stresses within the polymer-based binder to reduce part twist caused by stress and relaxation of polymer chains in the composite.

19 . The method according to claim 18 , further comprising:

depositing a fluidly interconnecting distribution channel through the infill wall of one of the part and the sintering support; and

penetrating the fluid debinder throughout the distribution channel to debind the infill wall of the one of the part and the sintering support.

20 . The method according to claim 18 , further comprising:

depositing the walls to form a densification linking platform below the part and below the sintering support;

depositing the walls to form a second channel penetrating the densification linking platform; and

flowing debinding fluid through the second channel.

21 . The method according to claim 18 , further comprising:

depositing part release layers between the sintering supports and the part with a release composite including a ceramic particulate filler and a binder; and

depositing a second channel through the part release layer and to the access channel that permits debinding fluid flow through the part release layer to the sintering supports.

22 . The method according to claim 18 , further comprising:

locating the sintering supports and the part in a debinding chamber; and

cyclically filling and draining the debinding chamber using a fluid debinder, thereby repeatedly immersing the sintering supports and part.

23 . The method according to claim 22 , further comprising;

holding the sintering supports and the part immersed in the debinding chamber for a dwell time that permits the fluid debinder to flow through the first channels.

24 . A method of depositing material for additive manufacturing, comprising:

feeding a composite including a polymer-based binder and sinterable metal particles having a bimodal particle size distribution, a first mode of first mode particles having an average particle diameter equal to or lower than substantially 8 micrometers, and a second mode of second mode particles having an average particle diameter equal to or lower than substantially ½ micrometer;

forming layers of a part from the composite by deposition upon a prior deposition of layers of the part of the composite;

debinding at least a portion of the binder from the composite;

heating the part so formed from the composite to a necking temperature where the second mode particles neck by atomic diffusion and structurally connect to the first mode particles sufficient to partially cement a shape of the part; and

sintering the part so partially cemented at a sintering temperature where the first mode particles densify by substantially 12-24% of a volume of the part.

25 . The method according to claim 24 , further comprising:

depositing walls of the layers of the part by moving a deposition head to deposit the composite along adjacent and retrograde tool paths in retrograde directions, wherein the deposition of the composite along adjacent and retrograde paths positions residual stresses within the polymer-based binder to reduce part twist caused by stress and relaxation of polymer chains in the composite.

26 . The method according to claim 24 , further comprising:

forming layers of a densification platform from the composite below the part; and

linking the densification platform to the part by forming separable attachment protrusions of the composite between the densification linking platform and the part.

27 . The method according to claim 24 , further comprising:

forming layers of a sintering support from the composite below the part;

forming a part release layer between the sintering support and the part with a release composite including a ceramic particulate filler and a binder;

keeping the part, the part release layer, and the sintering support together as a unit during the debinding, the holding and the heating;

debinding the binder of the part release layer; and

after sintering, separating the part release layer and sintering support from the desired part.

28 . The method according to claim 24 , further comprising

depositing walls of the layers of the part to form a channel penetrating a wall of the part; and

flowing a debinding fluid about the penetrated wall and through the channel.

29 . The method according to claim 24 , further comprising:

locating the part in a debinding chamber; and

cyclically filling and draining the debinding chamber using a fluid debinder, thereby repeatedly immersing the part.