Question

what is cold slug well in plastic injection moulding machine

Answer 1

It's the small nub of plastic that cools and solidifies inside the nozzle tip during the cooling phase of theinjection cycle.

Answer 2

In a cold-runner mold, the cold slug forms inside the end of the nozzle where it touches the cold mold steel. The cold slug well received that plug of solidified plastic on the next shot.