Method of manufacturing hot runner system components of two materials

1. A method of making a retainer with a retaining portion and a seal ring portion for a hot runner nozzle, comprising the steps of:

forming a retaining portion from a first material having a thermal conductivity and a passageway for directing molten plastic therethrough;

forming a seal ring portion from a second material having a thermal conductivity lower than the thermal conductivity of the first material and a passageway for directing molten plastic therethrough;

aligning the seal ring portion to the retaining portion at a junction such that a surface of the seal ring portions abuts a surface of the retaining portion; and

fusing the retaining portion and the seal ring portion together at the junction.

2. The method of claim 1 , wherein the fusing is done by electron beam welding.

3. The method of claim 1 , further comprising the step of machining the fused retaining portion and the seal ring portion to a final configuration which removes material adjacent the junction.

4. The method of claim 1 , wherein the aligning is done by an alignment feature formed on the retaining portion and the seal ring portion.

5. The method of claim 4 , wherein the alignment feature is a ridge formed in either the retaining portion or the seal ring portion and a recess formed in the other of the retaining portion or the seal ring portion, the recess receiving the ridge to align the retaining portion and the seal ring portion.

6. A method of forming an injection molding nozzle tip retainer, comprising the steps of:

forming a first blank having a thermal conductivity for a first portion of the nozzle tip retainer;

forming a second blank having a thermal conductivity lower than that of the thermal conductivity of the first blank for a second portion of the nozzle tip retainer;

abutting the second blank against the first blank at a junction;

fusing the first blank and second blank at the junction; and

machining the fused first and second blanks to a configuration for the first portion and second portion of the nozzle tip retainer.

7. The method of claim 6 , wherein the fusing is done by electron beam welding.

8. A method for manufacturing a nozzle tip retaining piece for a hot runner system, the nozzle tip retaining piece having a first portion and a second portion, the method comprising the acts of:

selecting a first material having a thermal conductivity for the first portion of the nozzle tip retaining piece;

selecting a second material for the second portion having a thermal conductivity lower than the thermal conductivity for the first portion;

permanently joining the first portion to the second portion; and

thereafter, machining at least one of the first or second portions of the nozzle tip retaining piece.

9. The method for manufacturing a nozzle tip retaining piece according to claim 8 , wherein the act of permanently attaching is performed by electron beam welding.

10. The method for manufacturing a nozzle tip retaining piece according to claim 9 , further comprising the act of providing an internal passageway through the first and second portions for molten plastic to pass therethrough.

11. A method of manufacturing a hot runner nozzle tip retainer, comprising the acts of:

machining a first blank having a thermal conductivity for a first portion of the nozzle tip retainer, wherein the first portion has an internal bore;

machining a second blank having a thermal conductivity lower than that of the first blank for a second portion of the nozzle tip retainer, wherein the second blank has an internal bore in fluid communication with the internal bore of the first portion;

abutting the second blank against the first blank at a junction;

fusing the first blank and second blank at the junction; and

thereafter, machining the fused first and second blanks to a configuration for the first portion and second portion of the nozzle tip retainer.

12. The method of claim 11 , wherein the fusing is performed by electron beam welding.