Fastener is a kind of mechanical part which is used for fastening and connection and widely used. Fasteners are widely used in the industry, including energy, electronics, electrical appliances, machinery, chemical industry, metallurgy, mold, hydraulic and other industries. Various fasteners can be seen on various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemical industry, instruments and supplies, and are the most widely used mechanical foundation. It is characterized by various varieties, specifications, different performance and use, and the degree of standardization, serialization and generalization is also very high. Therefore, some people call a kind of fastener which has national standard as standard fastener or referred to as standard fastener.