Cooling & trim defect
Bowing in thermoforming
Also called: Bow, cupping
Bowing is a specific form of warp where a panel curls or cups along its length or width, common on large, shallow, flat parts where there is little geometry to hold the shape.
Why it happens
- One face cooling faster than the other
- Large unsupported flat spans
- Residual stress from uneven stretching
- Trimming before the part has fully stabilised
How to fix & prevent it
- Balance cooling on both faces of the sheet
- Add a slight crown, ribs or a formed lip for stiffness
- Let parts stabilise fully before trimming and stacking
- Even the heating so the sheet stretches uniformly
How Indu prevents it: We add subtle crowns and stiffening features to large flat panels and let parts fully stabilise before 5-axis trimming, so they stay flat and true.
Troubleshooting help
Fighting bowing 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