Method for making a pressed part with separations or voids
The present invention is a process for producing molded parts from a polymeric powder or metallic powder, wherein the molded part has a separation or a void. The separation or void is formed by inserting a separator or void-forming material into the die cavity before, during or after filling the die cavity with the powdered molding material that is to form the pressed part. After the pressed part is formed the separator or void-forming material is removed to provide the separation or void.
1. A process for producing a seal ring with one or more complete separations in said seal ring, said process comprising:
(a) filling a die cavity in one or more steps with a powdered polymer;
(b) inserting into the die cavity after said filling, a separator material, having a thickness less than or equal to 1.0 mm, at one or more places at a location of desired separation of said seal ring;
(c) compressing the powdered polymer and the separator material in a mold to form said seal ring;
(d) removing said seal ring from said mold; and
(e) removing said separator material from said seal ring;
wherein said seal ring separations are complete separations; and wherein the opposing ends at the separation in the part have a rough, irregular surface with one end precisely complementary to the other, thereby providing a mating surface.
2. A process according to claim 1 , wherein the separator material is in the form of a film or a sheet.
3. A process according to claim 1 , wherein the separator material is in the form of a tube or column.
4. A process according to claim 1 , wherein said powdered polymer comprises a material selected from the group consisting of a powdered metal, a powdered polymer, and a powdered ceramic.
5. A process according to claim 4 , wherein said powdered polymer- comprises fillers and additives.
6. A process according to claim 4 , wherein said powdered polymer comprises powdered polyimide.
7. A process according to claim 2 or 3 , wherein the separator material comprises polymer, inorganic, metallic, ceramic, or fibrous material.
8. A process according to claim 4 , wherein the separator material comprises fibrous material comprised of paper, cardboard or cloth.
9. A process according to claim 1 , wherein sintering step is used to remove the separator material from the seal ring.
10. A process according to claim 8 , wherein the separator material is flat, V-shaped, curved shaped, or pleated shaped.
11. A process according to claim 9 , wherein the separator material has a thickness less than or equal to 0.1 mm.
12. A process according to claim 1 , wherein the seal ring is formed using compression molding.