Two-part polymer ammunition casing
A method of manufacturing a casing for an ammunition cartridge includes injection molding a first polymer forming a first part of the casing. The first part is cylindrically shaped along a longitudinal axis extending from a projectile end opposite a stepped end. The stepped end forms a first end of a mechanical connection. A portion of the injection mold is removed and an additional injection mold is disposed about the stepped end of the first end of the first part and a second polymer injected forms a second part of the casing. The second part includes a second stepped end forming a second end of the mechanical connection. The first and second end are mechanically locked together preventing a separation of the first part from the second part. A thermal swagging tool forms a conical tapered region along the projectile end of the first part.
1. A method of manufacturing a casing for an ammunition cartridge, the method comprising the steps of:
providing an injection mold;
utilizing the injection mold, injection molding a first polymer forming a first part of the casing, wherein the first part of the casing is generally cylindrically shaped along a longitudinal axis extending from a projectile end opposite a stepped end, the stepped end forming a first end of a mechanical connection;
removing at least a portion of the injection mold exposing the stepped end of the first end of the first part;
disposing an additional injection mold about the stepped end of the first end of the first part;
utilizing the additional injection mold, injection molding a second polymer forming a second part of the casing, wherein the second part includes a second stepped end forming a second end of the mechanical connection;
wherein the first end and the second end are mechanically locked together preventing a separation of the first part from the second part;
providing a thermal swagging tool; and
utilizing the thermal swagging tool, forming a conical tapered region along the projectile end of the first part.
2. The method of claim 1 , wherein the stepped end of the first part includes a first annular face disposed perpendicular to the longitudinal axis and open facing towards the projectile end.
3. The method of claim 2 , wherein the second stepped end of the second part includes a second annular face disposed perpendicular to the longitudinal axis and open facing away from the projectile end.
4. The method of claim 3 , wherein the first annular face is in direct contact with the second annular face forming the mechanical connection.
5. The method of claim 1 , wherein the first polymer and the second polymer are not the same material type.
6. The method of claim 1 , wherein the second polymer comprises ceramic or metal powder additives and the first polymer does not comprise ceramic or metal powder additives.
7. The method of claim 6 , wherein the first and the second polymers are the same material type.
8. The method of claim 6 , wherein the first polymer and the second polymer are not the same material type.
9. The method of claim 1 , wherein the injection molding of the second polymer forming the second part includes forming a casing base disposed opposite the second stepped end of the second end.
10. The method of claim 9 , wherein the injection molding of the casing base includes forming a primer retention feature and a flash hole leading to an inside of the casing.
11. The method of claim 9 , wherein a primer retention feature and a flash hole leading to an inside of the casing are machined after the injection molding of the second polymer forming the second part.
12. The method of claim 1 , wherein the second polymer comprises a base resin of polypropylene, polyethylene, high density polyethylene and/or acetal.
13. The method of claim 12 , wherein the second polymer comprises an additive of carbon nanotubes and graphene platelets in a percentage by weight of 0.01 to 30.0 percent.
14. The method of claim 1 , wherein the second polymer comprises a base resin of nylon, ABS, PET, polyamides, PEEK, general co-polymers, general homo-polymers.
15. The method of claim 14 , wherein second the polymer comprises an additive of fiberglass filled materials and/or Talc filled materials.
16. The method of claim 1 , wherein the second polymer does not comprise PEEK.
17. A method of manufacturing the ammunition cartridge utilizing the casing of claim 10 , now including the step of disposing a primer inside the primer retention feature, adding a propellant inside the casing and disposing a projectile in the projectile end of the casing.
18. A method of manufacturing the ammunition cartridge utilizing the casing of claim 11 , now including the step of disposing a primer inside the primer retention feature, adding a propellant inside the casing and disposing a projectile in the projectile end of the casing.