A method of making a selected sized integral injection molding heated nozzle comprising the steps of:
- (a) making a steel rear portion having a forward end, a rear end, and a generally cylindrical outer surface, the outer surface having a continuous convoluted first groove extending to receive an electrical heating element therein, having,
- (b) selecting at least a first elongated steel forward portion made with a forward end, a rear end, and a generally cylindrical outer surface, the outer surface having a continuous convoluted second groove extending to receive an electrical heating element therein, the first elongated forward portion having a melt bore extending therethrough from an inlet at the rear end to an outlet at the forward end, the selected first forward portion being of a predetermined desired outer diameter and length from the forward end to the rear end, the melt bore inlet of the selected first forward portion being of a predetermined desired diameter,
- (c) machining the rear portion to provide a melt channel extending therethrough from an inlet to an outlet at the forward end, the melt channel outlet having a diameter equal to the diameter of the melt bore inlet of the first forward portion,
- (d) rotating the first forward portion relative to the rear portion to a position wherein the second groove is in continuous alignment with the first groove, and joining the rear end of the first forward portion to the forward end of the rear portion in this position, wherein the melt bore inlet of the first forward portion is in alignment with the melt channel outlet of the rear portion,
- (e) winding an electrically insulated heating element in the first and second grooves which extend continuously from the outer surface of the rear portion to the outer surface of the first forward portion,
- (f) applying brazing material where the rear end of the first forward portion joins the forward end of the rear portion, and applying a coating of binder and metallic powder to the outer surfaces of the rear portion and the first forward portion, and
- (g) heating the joined rear portion and first forward portion under a partial vacuum in the presence of an inert gas for a period of time and to a temperature sufficient to melt the brazing material to integrally braze the first forward portion to the rear portion and sufficient to melt the metallic powder and remove the binder to form a protective metallic coating on the outer surfaces of the rear portion and the first forward portion.