Q: Why did a zipper tooth break off during use?
A broken tooth is either a strength question or a handling question. Where it broke and how the fracture face looks will usually tell you which, and that decides whether to change the specification or the handling.
- Note whether the break is at the slider rest position, at a fold, or at random.
- Examine the fracture face: a bright granular break suggests a single overload, a dull worn break suggests fatigue.
- Check the slider for a burr or a bent flange that could lever a tooth.
- Review the wash and dry process, because heat and tumbling can embrittle some moulded teeth.
- Test a sample from the same lot with a simple flex and pull routine to see whether failures repeat.
Repeat failures at the same position usually mean a mechanical cause in the garment or the slider. Isolated breaks spread across a lot point to material and should be raised with the maker using the lot number and photographs. Do not mix parts from different lots when you build the comparison sample.