Marks hide, they rarely vanish
Plan a hidden belt. Do not promise a mark-free class-A face.
Ejection design
Ejection Design: Release the Part Without Cosmetic Damage
Identify hidden ejection zones on CAD. DFM review comments before the layout locks. Marks cannot always be eliminated, but they can be hidden.
Design guideline
The part has to leave without a fight
Ejection happens while the part is still warm. Uneven push warps flat covers. Deep cores need enough area or they vacuum-hold. This page owns the system. Pin placement owns where each pin lands.
Robot grip points can replace some pin marks when automation is in scope. Ejector pin placement owns the map. Ejector pin marks own the defect. Draft angle owns release. DFM review needs keep-off faces and deep cores.
This spoke owns the system: pins, stripper plates, sleeves. The design guide hub lists every topic.
Roles
Which page answers which ejection question
Stay here for the system. Open a sibling for pin map, the mark, or draft.
| Page | Use it for |
|---|---|
| Ejection design (this page) | Pins, strippers, sleeves as a system |
| Ejector pin placement | Where each pin may land |
| Ejector pin marks | The witness defect |
| Draft angle | Why the part sticks |
| Warpage | Uneven push on a flat cover |
| Ribs | Crossings that can take a pin |
| Texture draft | Grain that scuffs on eject |
| DFM review | CAD check before steel |
Checks
What DFM review looks for on ejection
Qualitative checks. No figure on this page is a NetProto specification.
Uneven push warps
A flat cover needs balanced area. Open warpage if that is the defect.
Deep cores stick
Vacuum hold needs area, draft, or air assist. Flag deep pockets.
Who approves locations
Say if cosmetics are critical. Pin placement owns the map.
Decision
A pin grid on a gloss face versus a hidden ejection belt
Wrong: push wherever the steel is easy. Right: give a hidden zone, then let tooling pick pins, stripper, or sleeves.
What goes wrong
- Pins on a class-A cover
- A deep core with no draft and no eject area
- Assume marks can be polished away on every face
What to try first
- Mark hidden ribs and flanges
- Draft deep cores and flag vacuum risk
- Open pin placement for the keep-off map
RFQ
Send these notes with CAD for an ejection review
The quote can start from CAD alone. These notes make the DFM pass specific.
Class-A keep-off faces
Hidden zones that can take pins or a stripper
Deep cores that may vacuum-hold
Flat covers that cannot warp at demold
Whether robot grip is in scope
Who approves pin or stripper locations
Related
Related design guidelines
Stay on this spoke for its question. Open a sibling for the neighbor topic or the CAD check.
Ejector pin marks
The witness defect.
Ejector pin marksEjector pin glossary
What a pin is.
Ejector pin glossaryWarpage
Uneven push on a flat cover.
WarpageDFM review
How NetProto reads ejection zones on CAD.
DFM reviewFAQ
Ejection design FAQ
Can ejection marks be eliminated?
Rarely on every face. Hide them on a rib or flange. The defect page owns the mark when it shows.
Does ejection cause warp?
Uneven push on a warm cover can. Balance the area. Open warpage if that is the defect.
Who approves pin locations?
Say on the RFQ if cosmetics are critical. Pin placement owns the map. This page owns the system.
Pins, stripper, or sleeves?
Tooling picks from the part. Give a hidden zone and flag deep cores. This page does not publish a catalog.
Do I need to design the ejector plate?
No. Mark keep-off and hidden zones. The tooling team designs the plate.
How is this page different from pin placement?
This spoke owns the system. Pin placement owns where pins land. DFM review checks CAD.
Next step
Upload CAD for DFM review of ejection zones
Share keep-off faces and deep cores so review can plan release before quoting.