Method of molding complex structures using a sacrificial material

Abstract

A number of processes are described herein that can be used to form complex parts with undercuts and the like. In one embodiment, a multi-shot process is used to form the sacrificial component and inject the PIM feedstock. The processes described herein may reduce the number and/or severity of defects in the final part.

1 . A method of molding a part comprising:
 molding a sacrificial component;   molding the part over the sacrificial component; and   wherein the sacrificial component is molded in one or more shots in a molding press and the part is molded over the sacrificial component in one or more additional shots in the molding press.   
   
   
       2 . The method of  claim 1  wherein the sacrificial component is molded in one or more shots in a molding press and the part is molded over the sacrificial component in one or more additional shots in the molding press. 
   
   
       3 . The method of  claim 1  comprising debinding the part. 
   
   
       4 . The method of  claim 3  wherein debinding the part includes catalytically debinding the part. 
   
   
       5 . The method of  claim 3  wherein debinding the part includes thermally debinding the part. 
   
   
       6 . The method of  claim 3  wherein debinding the part includes chemically debinding the part. 
   
   
       7 . The method of  claim 1  comprising sintering the part. 
   
   
       8 . The method of  claim 1  wherein the part includes a binder and the sacrificial component and the binder have at least substantially the same composition. 
   
   
       9 . The method of  claim 1  wherein the sacrificial component includes polyacetal based material. 
   
   
       10 . The method of  claim 1  wherein the part is made of injection molded plastic. 
   
   
       11 . A multi-shot process for powder injection molding a part comprising:
 molding a sacrificial component in one or more shots in a molding press; and   molding the part over the sacrificial component in one or more shots in the molding press.   
   
   
       12 . The multi-shot molding process of  claim 11  wherein the part includes a binder and the sacrificial material and the binder are capable of being removed simultaneously from the part. 
   
   
       13 . The multi-shot molding process of  claim 11  comprising debinding the part. 
   
   
       14 . The multi-shot molding process of  claim 13  wherein debinding the part includes catalytically debinding the part. 
   
   
       15 . The multi-shot molding process of  claim 11  comprising sintering the part.