Insert for an injection molding apparatus

1. An injection molding apparatus comprising:

a manifold having an inlet and at least one melt channel in fluid communication with the inlet;

a cylindrical bore in the manifold intersecting the melt channel;

an expandable cylindrical sleeve co-axial with and seated in the cylindrical bore, the sleeve having a sleeve opening in communication with the melt channel; and

a cylindrical insert co-axial with and seated in the sleeve, the insert defining a melt duct with an insert inlet opening in fluid communication with the sleeve opening and an insert outlet opening opposite the insert inlet opening;

wherein the sleeve has a coefficient of expansion and a thickness selected such that when the manifold, insert and sleeve are heated to an operational temperature, the sleeve expands to create a fluid tight seal between the manifold and the insert.

2. The apparatus of claim 1 , wherein the coefficient of expansion of the sleeve is greater than the coefficient of expansion of at least one of the manifold and the insert.

3. The apparatus of claim 2 , wherein the coefficient of expansion of the sleeve is greater than the coefficient of expansion of both the manifold and the insert.

4. The apparatus of claim 1 , wherein the sleeve expands more, in absolute terms, than at least one of the manifold and the insert.

5. The apparatus of claim 4 , wherein the sleeve expands at least 10% more, in absolute terms, than at least one of the manifold and the insert.

6. The apparatus of claim 5 , wherein the sleeve expands at least 40% more, in absolute terms, than at least one of the manifold and the insert.

7. The apparatus of claim 1 , wherein the operational temperature is about 150° C. or greater.

8. The apparatus of claim 7 , wherein the operational temperature is about 300° C. or greater.

9. The apparatus of claim 1 , wherein the sleeve is dimensioned to slidably receive the insert in a press fit when the sleeve and insert are at the same temperature.

10. The apparatus of claim 1 , wherein the sleeve is dimensioned to slidably receive the insert in a press fit when the temperature of the insert is lower than the temperature of the sleeve.

11. The apparatus of claim 1 , wherein the sleeve is dimensioned to engage the bore in a press fit when the sleeve and manifold are at the same temperature.

12. The apparatus of claim 1 , wherein the sleeve is dimensioned to engage the bore in a press fit when the temperature of the sleeve is lower than the temperature of the manifold.

13. The apparatus of claim 1 , wherein the sleeve is made of a material chosen from the group comprising alloys of stainless steel, beryllium, copper, silver, and aluminum.

14. The apparatus of claim 13 , wherein the material is chosen from copper, aluminum and stainless steel alloys.

15. The apparatus of claim 1 , wherein the thickness of the sleeve expands more than 0.00 17 mm per mm of thickness of the sleeve per degree ° C. increase in temperature.

16. An injection molding insert assembly for redirecting melt from a manifold melt channel comprising:

an expandable cylindrical sleeve having a sleeve opening in a wall thereof in fluid communication with the manifold melt channel; and

a cylindrical insert coaxial with and press fit within the sleeve, the insert defining a melt duct with an insert inlet opening in fluid communication with the sleeve opening for receiving the melt from the manifold melt channel and an insert outlet opening at an opposite end of the melt duct from the insert inlet opening;

wherein the sleeve is of a material that has a first coefficient of expansion and the insert is of a material that has a second coefficient of expansion.

17. The insert assembly of claim 16 , wherein the first coefficient of expansion of the sleeve material is greater than the second coefficient of expansion of the insert material.

18. The insert assembly of claim 17 , wherein the sleeve expands more, in absolute terms, than the insert.

19. The insert assembly of claim 18 , wherein the sleeve expands at least 10% more, in absolute terms, than the insert.

20. The insert assembly of claim 18 , wherein the sleeve expands at least 40% more, in absolute terms, than the insert.

21. The insert assembly of claim 16 , wherein the sleeve is dimensioned to slidably receive the insert in the press fit when the sleeve and insert are at the same temperature.

22. The insert assembly of claim 16 , wherein the sleeve is dimensioned to slidably receive the insert in the press fit when the temperature of the insert is lower than the temperature of the sleeve.

23. The insert assembly of claim 16 , wherein the sleeve is made of a material chosen from the group comprising alloys of stainless steel, beryllium, copper, silver, and aluminum.

24. The insert assembly of claim 16 , wherein the thickness of the sleeve expands more than 0.0017 mm per mm of thickness of the sleeve per degree ° C. increase in temperature.

25. An injection molding apparatus comprising:

a manifold having an inlet and at least one melt channel in fluid communication with the inlet;

a cylindrical bore in the manifold intersecting the melt channel;

an expandable cylindrical sleeve co-axial with and seated in the bore, the sleeve having a sleeve opening in communication with the melt channel; and

a cylindrical insert co-axial with and seated in the sleeve, the insert defining a melt duct with an insert inlet opening in fluid communication with the sleeve opening and an insert outlet opening opposite the insert inlet opening;

wherein the outer diameter of the insert, thickness of the sleeve, inner diameter of the cylindrical bore, and material of the insert, sleeve and manifold, are each selected such that when the manifold, sleeve and insert are heated to an operational temperature, the sleeve expands to create a fluid tight seal between the manifold and the insert.