PA is material PM is model CM is specification.
Nut is nut, and bolt or screw screw together used to tighten the role of the parts, all manufacturing machinery must use a component according to the different materials, divided into carbon steel, stainless steel, non-ferrous metal (such as copper) and other major types.
Screw is a tool to tighten the machine parts step by step by using the physics and mathematics principle of the bevel circular rotation and friction of the object.Screw is a general term for fasteners.Screws are indispensable industrial necessities in daily life: extremely small screws used in cameras, glasses, clocks, electronics, etc.General screws for televisions, electrical products, Musical Instruments, furniture, etc.For projects, buildings and Bridges, large screws and nuts are used.Transportation equipment, aircraft, tram, automobile and so on are used with screws of both sizes.Screws have important tasks in the industry, as long as there is industry on the earth, the function of the screw is always important.Screw is a common invention in people's production and life for thousands of years. According to the application field, it is the first major invention of human beings.