Q: What causes a grinding noise when I close a zipper?
Grinding is the sound of metal or moulded parts rubbing under load. It is not normal, and it usually appears at one point of travel or in one direction, which makes it easier to locate than a general stiffness complaint.
- Close and open the zipper by hand beside your ear and note whether the noise occurs on close, on open, or both.
- Examine the slider body for a bent flange, a burr or trapped grit; a burr often leaves a bright line on the tape edge.
- Inspect the teeth at the noisy section for high or misaligned elements rubbing the slider wall.
- Clean the chain with a soft brush and retest, because grit from finishing or stone wash is a common cause.
- Fit a known-good slider of the same size to the same chain and see whether the noise follows the slider.
If a clean, straight chain still grinds with a new slider, the chain dimensions are suspect and should be measured against the maker's drawing. Record where the sound occurs and which garment operation was in progress, since that record decides whether the claim goes to the zipper maker or to the sewing line.