Ordliste
Ejector pin — definition
A pin that pushes the solidified part out of the die when it opens.
The part shrinks onto the cores as it solidifies and therefore grips the die. The ejector pins push it free.
The pins must sit where the part can take the load — on ribs, bosses or heavy sections, not in the middle of a thin face where they will dimple it. They always leave a mark.
On a visible part the placement of ejector points is therefore a design decision rather than a toolmaker decision, and it has to be made before the tool is built.