Key principles.
Hidden surface
Place ejector pins on non-cosmetic surface (B-side).
3-6 mm typical
Standard ejector pin diameter. Matches force needed.
Distribute force
Even ejector force distribution prevents part distortion.
Slight depression
Ejector pins leave 0.05-0.2 mm depression. Hidden = OK.
Avoid weak spots
Don't place ejector pins where material weak (gates, weld lines).
Through smaller
Through-hole ejection cleanest. Surface depression unavoidable on flat areas.
FAQ
Non-cosmetic surface (back, hidden side). Discuss with tooling engineer.
0.05-0.2 mm depression typical. Visible if cosmetic surface, hidden if back.
3-6 mm standard. Large parts use larger pins for sufficient force.
Cannot eliminate completely on most parts. Choose location to hide.
Cylindrical features ejected by sleeve, no pin marks on visible surface.
Standard ejector pin design, no premium. Custom ejection (sleeve, stripper) adds 20-50% mold cost.
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