Non-electrolytic zinc sheet coating – technical requirements and inspection of socket shoulder screw dimensions
The zinc-coated layer of the hexagon socket shoulder screw does not exceed the part (basic size) in the case of external threads. After coating, the ordinary thread is in accordance with the provisions of GB/T 3934: the external thread is inspected separately with the tolerance zone position h or H. When the coated thread is tested with a ring gauge, the maximum allowable torque is: 0.001 (N·m). Where d is the nominal diameter of the thread (mm). Other socket shoulder screw dimensions are only applicable before coating. In order to achieve the specified corrosion resistance, if the minimum coating thickness is specified, the thickness range of the zinc coating layer shall be such that the socket shoulder screw dimensions is substantially equal to the minimum coating thickness. Therefore, the estimated maximum zinc coating thickness is twice the minimum required coating thickness. See Table 1. The minimum basic deviation of the thread applied for coatin...