Sprue, Cold Slug Weld, Runner, and Gates

The sprue connects the machine nozzle to the mould. It provides a passageway for the plastics to travel.


Opposite the sprue is a circular depression, or a cold slug weld, that captures the first portion of the material injected into the mould. The runners then provide a passageway to deliver the molten plastics material to the vicinity of the mould cavity.

The gate is an opening at the end of the runner through which material enters the cavity and moulded parts are produced.