Small knowledge of automotive fasteners

Surface treatment and inspection of fasteners. Surface treatment refers to the process of forming a covering layer on the surface of fasteners through some methods. After surface treatment, fasteners can show a more beautiful appearance, and the anti-corrosion ability of fasteners will be improved. The surface treatment methods of fasteners are as follows:

Mechanical plating of fasteners refers to impacting the surface of fasteners with the powder of coated metal by specific physical and chemical means, so that the coated metal forms a coating on the surface of fasteners in the form of cold welding to achieve the effect of surface treatment. Mechanical plating of fasteners is mainly applicable to screws, nuts, gaskets and other spare parts.

The hot-dip galvanizing of fasteners is to immerse the fasteners composed of carbon steel into the molten zinc plating bath with a heat of about 510 ℃, so that the iron zinc alloy on the surface of fasteners will be transformed into passivated zinc, so as to obtain the surface treatment effect. The price of hot-dip galvanizing of fasteners is higher than that of electroplating, about 1.5 to 2 yuan per kilogram.

Electroplating of fasteners refers to immersing the parts to be electroplated in a specific aqueous solution, which will contain some deposited metal compounds. In this way, after passing through the aqueous solution with current, the metal substances in the solution will precipitate and adhere to the immersed parts of fasteners. Electroplating of fasteners generally includes zinc plating, copper, nickel, chromium, copper nickel alloy, etc.

The main purpose of fastener surface treatment is to enable the fastener itself to obtain anti-corrosion ability, so as to increase the reliability and adaptability of the fastener. Therefore, the quality judgment of fastener surface treatment is mainly to check whether the anti-corrosion ability of the fastener is effectively increased and whether the increase range meets the expected requirements.