Hide on ribs and flanges
Class-A faces are keep-off unless you accept the mark.
Ejector pin placement
Ejector Pin Placement: Hide Witness, Support the Push
Upload a keep-off map. DFM review comments before pin layout is locked. The ejection-design page owns stripper plates and sleeves.
Design guideline
The mark lands where you allow it
Pin placement is a cosmetic choice as much as a mold choice. Pins on glossy faces show even when flush. Texture hides minor witness. This page owns where pins land, not the whole ejection system.
Ejector pin placement decides where witness marks appear. Pin clusters around deep ribs need support without punching through thin walls. Ejection design owns the system. Ejector pin marks own the defect. The ejector pin glossary defines the pin. DFM review needs keep-off faces.
This spoke owns placement. The design guide hub lists every topic.
Roles
Which page answers which pin question
Stay here for where pins land. Open a sibling for the system, the mark, or the glossary.
| Page | Use it for |
|---|---|
| Ejector pin placement (this page) | Where pins may land |
| Ejection design | Pins, strippers, sleeves as a system |
| Ejector pin marks | The witness defect |
| Ejector pin glossary | What a pin is |
| Texture draft | Grain that can hide a small mark |
| Rib design | Rib feet as pin landing zones |
| Draft angle | Draft that helps the part leave |
| Wall thickness | Pins on a thin skin dent |
| DFM review | CAD check before steel |
Checks
What DFM review looks for on pin placement
Qualitative checks. No figure on this page is a NetProto specification.
Support, do not punch
Pins on a thin skin dent or pierce. Sit them on a rib crossing.
Size is tooling
Pin diameter is not a published spec. Placement is the buyer input.
Sleeves are a system choice
Sleeve ejectors belong on the ejection-design page.
Decision
Pins on a show surface versus a hidden belt
Wrong: a pin grid on a gloss cover. Right: a hidden belt on ribs, then let tooling size the pins.
What goes wrong
- Pins on a glossy class-A face
- Pins on a thin skin with no rib
- Change pin size after T1 as if it were free
What to try first
- Mark keep-off faces
- Give a hidden flange or rib crossing
- Open ejection design if you need a stripper or sleeve
RFQ
Mark these on CAD before uploading for DFM review
The quote can start from CAD alone. These notes make the DFM pass specific.
Class-A keep-off faces
Hidden ribs or flanges that can take pins
Thin walls that cannot take a pin
Texture that may hide a small mark
Whether a stripper or sleeve is acceptable
Who approves pin 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 glossaryDFM review
How NetProto reads keep-off maps on CAD.
DFM reviewFAQ
Ejector pin placement FAQ
Where should ejector pins land?
On hidden ribs, flanges, and other keep-in zones. Keep them off class-A faces unless you accept the mark.
Can pin size change after T1?
A late change is steel work. Lock keep-off faces before the layout freezes.
Do pins cause flash?
Poor shutoff or worn pins can. The defect page owns the mark. This page owns where they sit.
Are sleeve ejectors always better?
No. They are a system choice for bosses and rounds. Open ejection design.
Who approves pin locations?
Say on the RFQ if cosmetics are critical. DFM review comments on CAD.
How is this page different from ejection design?
This spoke owns where pins land. Ejection design owns the system. DFM review checks CAD.
What information should I mark on CAD for pin placement review?
Show class-A keep-off faces, hidden rib crossings that can take pins, thin walls that cannot, and who approves the layout. Upload CAD so DFM review can comment before quoting.
Next step
Upload CAD for DFM review of pin keep-off zones
Share class-A faces and hidden belts so review can place pins before quoting.