Shutoff at the split
Pin alignment and flash control set hole roundness.
Through holes
Through Holes: Open Both Ends to the Mold Split
Mark hole patterns and mates on CAD. DFM review checks pin shutoff, nearby thin walls, and whether the hole is really through.
Design guideline
Both ends reach the split
A through hole is open on both ends so a core pin can shut off at the split. That vents better than a blind pocket. Alignment and flash at the split control roundness.
A through hole opens both ends to the mold split so a core pin can shut off. Holes near thin walls need extra review so pins do not punch through during fill or ejection. Blind holes own closed pockets. Side holes own off-draw openings. Parting line owns the seam the pin shuts on. DFM review needs the pattern on CAD.
This spoke owns on-draw through holes. The design guide hub lists every topic.
Roles
Which page answers which through-hole question
Stay here for holes open at both ends. Open a sibling for blind, side, the split, or ejection.
| Page | Use it for |
|---|---|
| Through holes (this page) | Both ends open to the split |
| Blind holes | Closed on one end |
| Side holes | Axis off the pull |
| Parting line | Where the pin shuts off |
| Venting | Why an open pin vents better |
| Ejection design | Pins and hole pins share steel space |
| Bosses | A boss may be through or blind |
| Draft angle | Draft on the hole wall |
| Hole shapes | Pin, slot, or window. Not through versus blind. |
| DFM review | CAD check before steel |
Checks
What DFM review looks for on through holes
Qualitative checks. No figure on this page is a NetProto specification.
Draft on the wall
A through hole still needs a release plan on the pin.
Near thin walls
A pin next to a thin skin can blow through. Mark those holes.
Threads are a different page
A molded thread or an insert is not a plain through hole. Open molded-in threads or boss design for those features.
Decision
A through hole on the split versus a blind pocket
Wrong: call every hole through when one end is closed. Right: open both ends if you want pin shutoff and natural vent.
What goes wrong
- A hole that stops short and traps air
- A through hole next to a paper-thin wall
- An angled hole treated as on-draw
What to try first
- Open both ends to the split when function allows
- Keep stock around the pin
- Open side-holes if the axis is off pull
RFQ
Mark these on CAD before uploading for DFM review
The quote can start from CAD alone. These notes make the DFM pass specific.
Hole pattern and which holes are mates
Intended pull and parting
Holes near thin walls
Whether any hole is actually blind
Whether any hole is off-draw
Thread or insert intent, if any
Related
Related design guidelines
Stay on this spoke for its question. Open a sibling for the neighbor topic or the CAD check.
DFM review
How NetProto reads hole patterns on CAD.
DFM reviewFAQ
Through holes FAQ
What is a through hole in molding?
A hole open on both ends so a core pin can shut off at the split. It vents better than a blind pocket.
Can through holes be threaded?
A thread is a different feature. Open molded-in threads or the insert spokes. This page owns the plain opening.
Do through holes need draft?
The hole wall still needs a release plan. The draft page owns those faces.
Can holes be angled to the pull?
Then they may become side holes. Open that spoke.
Do through holes flash at the split?
They can if the pin does not shut off clean. Mark mates and cosmetics.
How is this page different from blind or side holes?
Blind holes are closed on one end. Side holes are off-draw. This spoke owns on-draw through openings. DFM review checks CAD.
What information should I mark on CAD for through holes?
Show hole pattern, which holes are mates, pull direction, and whether any hole is actually blind or off-draw. Upload CAD so DFM review can check shutoff before quoting.
Next step
Upload CAD for DFM review of through holes
Share hole patterns, mates, and pull direction so review can check shutoff before quoting.