Hot-dip galvanizing is an effective metal corrosion resistance method, is to rust after the screws immersed in 500 ° C around the melting of zinc liquid, so that the surface of the nut attached to the zinc layer, which play a preservative effect. Hot-dip galvanizing layer is thick(usually 40um or more). Considering its impact on the thread accuracy, the hole size of hot dip galvanized nut is slightly larger than the general nut when producing. The upper limit of the thickness of the final control of the edge, 0.5mm thicker than the upper limit of the specification.
1) Metric (DIN, ISO, GB) is divided into 6H, 6G level. Usually the case is 6H level. Metric Japanese standard (JIS) is divided into Ⅰ grade, Ⅱ grade, Ⅲ grade and so on. Usually the situation is Ⅱ.
2) British Standard(BS) for 1B, 2B, 3B, and 2B level in general.