Forming defect
Bridging in thermoforming
Bridging is when the softened sheet stretches across the mouth of a narrow or deep cavity rather than drawing down into it, leaving a gap or an unformed pocket at the base of the feature.
Why it happens
- Narrow, deep cavities the sheet cannot reach into
- Insufficient vacuum or too few vacuum holes at the cavity base
- Sheet too cool and stiff to stretch fully
- No plug assist to push material into the recess
How to fix & prevent it
- Increase vacuum and add vent holes at the base of deep features
- Use a plug assist to physically push material into the cavity
- Raise the local sheet temperature so it stretches further
- Widen the cavity or add draft so material can flow in
How Indu prevents it: Our tool room drills fine vacuum and vent holes exactly where deep features need them, and we build matched plug assists so even deep-draw cavities fill cleanly.
Troubleshooting help
Fighting bridging 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