Special-shaped and special-shaped standard parts such as special-shaped bolts and nuts refer to non-standard bolts and non-standard nuts that are not produced in accordance with various standards (national standard, American standard, Japanese standard, etc.). Non-standard parts mainly refer to other parts that are freely controlled by the enterprise except that the country has not set strict standard specifications and has no relevant parameter regulations. There are many varieties of non-standard parts, and there is no very standardized classification at present. Generally, companies develop independently based on market needs and their own brand development to extend the vitality of products.

The processing flow of special-shaped bolts is not the same as that of ordinary screws. Some non-standard special-shaped screws cannot be directly punched out with a cold heading machine. They need to be processed by lathes, machine tools and other machines, so the processing flow will be more There are a lot more screws in general. Of course, after the non-standard special-shaped screw is processed, its surface treatment methods such as heat treatment and electroplating are similar to the electroplating methods of ordinary screws. The electroplating can be colored zinc or black zinc or blue and white zinc.