What is a hot runner?

- Mar 08, 2018 -

A hot runner is a heated nozzle and manifold assembly installed on plastic injection molds.This assembly allows the plastic charge material left in the feed mechanism to remain fluid after injection while the part itself cools and solidifies. Injection molds equipped with hot runners are more economical, with feature of shorter cycle time and less material wastage. These savings are possible due to the fact that the manifold and nozzles keep the plastic in them fluid between injection cycles, eliminating the wasted time and material associated with the solidified “runners” in conventional cold molds. Accordingly, hot runners usually make the mold more expensive to manufacture and run.