The prepared core pin is filled with a gas mixture, sealed and capped at the factory. When the pin is returned it is ready for immediate use in the mold.

End caps may be ordered to extend into a coolant channel or flush capped if an additional step is added to the head of the core.

a = .040"* b = .184"* c = .040"* d = .093", .125", .156", .187", .250", .312", .375", .437", .500"* l = length * Nominal Size

APPLICATION

Very often, when working with thermosetting or injection molding plastics, the ability of the molder to control temperature will determine the success or failure of the mold. Thermal problems can become so acute that they may actually endanger the mold itself; in less extreme cases a lack of thermal control will produce a molded item showing signs of shrinking, sinking or poor flow. The long cooling time necessary on some molds makes them economically impractical. Until now the best method of cooling molds is with water cooled core pins. With small mold sizes however, this system is at times marginal. Bubblers and fountains all contain small passages and channels where heat from the mold passes directly into the coolant. Because of the small size of some cores high heat density is present at this mold-fluid interface. The high heat density can often cause flash boiling which immediately precipitates impurities out of the fluid onto the passage wall in the form of scale. Scale will also form in the passages of bubblers which use very hard water whether or not there is any flash boiling. Deposits will begin to choke off these small channels and reduce efficiency causing what is known as "core pin aging." Eventually complete failure will result.

Because a NOREN PRODUCTS THERMAL PIN core is a completely sealed system, no scale can develop and no pin aging can occur. The thermal fill, acting as a heat transformer, spreads the heat out over a large area for cooling. This affords greater cooling efficiency.

CORE PIN PREPARATION

Core pins must be machined by the user before being sent to the factory to be filled. Drill out the center bore to the largest possible size within strength requirements; no more than one i.d. step is allowable. The ratio of diameters at the step should be no more than 2 to 1. If the pins are to be flush capped dimension "a" should be at least .080" and dimension "c" should be at least .090." For extended end caps, machine as shown in fig. 1 Dimensions in fig. 1 must be drilled to one of the diameters shown, with an allowable tolerance of (+.002; -.000) inch. The customer should indicate the length required (dimension 1).

The core pin should be hardened, ground and finished ready for use in the mold. The a, b, c, & d dimensions should be added after the core is hardened. Processing at the factory is carefully done at a relatively low temperature so that there is no change in hardness or finish. Some final polishing may be necessary.

OPERATION

Care should be taken that the center of the THERMAL PIN core is not ruptured by drilling, cutting or overheating. Since this is a pressure operated device, any rupture will cause it to become inoperative; these pins may be sent back to the factory for reprocessing. Each THERMAL PIN core comes with a temperature safety valve. This valve will release at 400°F without damaging the mold. Always avoid overheating the unit outside of the mold.