Thickness Tolerance: Thickness Tolerance (厚度公差)
The permitted variation in thickness between the tooth area and the tape area of a zipper. Thickness affects how flat the zipper lies in a seam, how it feeds through a sewing machine and how it looks under a press. Tight tolerance prevents steps and bulging at the seam, while loose tolerance causes uneven topstitching. Thickness is measured at defined points with a dial gauge and compared with the approved specification.