Injection molding apparatus

Abstract

Apparatus for forming objects from molten material includes a mold frame and a movable mold side having complementary faces that define molding cavities. The mold frame includes a mold housing having an internally heated manifold which has a molten plastic distribution channel system for conducting molten plastic to injection nozzle passageways, each having a restricted discharge nozzle that discharges the plastic into a molding cavity. Within each injection nozzle passageway is a heater probe which has an internal heater, preferably an electrical cartridge heater. The probe is secured by an integral seating flange to the mold housing to hold the probe coaxially aligned in the injection nozzle passageway and to hold the probe against shifting with thermal expansion and contraction of the manifold. The integral rear flange is positioned in front of manifold block and has a connecting passageway that communicates the manifold distribution channel with the injection nozzle passageway. The electrical cartridge heater is substantially lower in cost than external electrical band heaters used heretofore for heating plastic flowing internally through a probe. To reduce heat transfer from the probe to the manifold, air pockets are formed into surfaces of the probe that interface with the manifold.