Why this matters
Know why ejector pins leave visible marks, where placement actually matters, and how to flag cosmetic zones before the ejection layout is locked. Ejector pins push the finished part off the core after every cycle, and even a pin recessed or proud by a fraction of a millimeter leaves a visible witness mark where it contacted the part. The mark itself is close to unavoidable at the pin location; what is avoidable is having that location land on a face the customer actually looks at.
Buyer checks
Quote variables
| Quote variable | Why it changes the mold route |
|---|---|
| Cosmetic face map | Which surfaces are seen by the end user drives where ejector pins can and cannot land. |
| Part geometry for hidden ejection points | Ribs, bosses and gate/overflow areas give the tool designer places to hide pins without an alternate ejection method. |
| Pin size vs. wall thickness | Undersized pins for the part’s ejection load wear faster and produce more visible marks over the mold’s life. |
| Process packing pressure | Overpacking pushes material into pin clearances and can create or worsen marks independent of pin placement. |
Common mistakes
How to apply it
Mark cosmetic and hidden faces on the CAD before requesting a tooling quote, and ask specifically how ejector pins will be placed relative to those faces, since this is a design decision that is cheap before steel and expensive after. If the project is early, the guide can show whether the next move is CAD cleanup, DFM review, prototype tooling, production mold planning, export mold handoff or repair review.