411 REFERENCE · Wikibooks
Plastics Molding & Manufacturing/Cooling
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
The cooling phase started as soon as the injection phase ended.
The viscous plastic parts is cooled into a solid parts until it is hardened enough for ejection from mould.
Plus meanwhile the plastic is cooling down, the screw moves backward as it is preparing for next shot.