Cooling & trim defect
Nibs & mould mark-off in thermoforming
Also called: Pimples, vac-hole marks
Nibs are small raised pimples or dimples on the surface, usually where vacuum holes are too large, or where dust and debris on the tool transfer into the hot sheet.
Why it happens
- Vacuum holes larger than necessary
- Dust, swarf or release residue on the tool
- Rough spots or nicks in the mould surface
- Sheet too soft, flowing into hole openings
How to fix & prevent it
- Use the smallest effective vacuum-hole diameter
- Keep tools clean between cycles
- Dress out nicks; maintain a fine surface finish
- Tune temperature so the sheet does not flow into holes
How Indu prevents it: Our tool room drills minimal-diameter vacuum holes in the right places and maintains fine tool surfaces, keeping show faces free of nibs and mark-off.
Troubleshooting help
Fighting nibs & mould mark-off on a part?
Send your drawing, sample or a photo of the issue — our engineers will diagnose the cause and reply with the tooling, material and process fix, usually within 24 hours.
ISO 9001:2015 certified · Most quotes back within 24 hours