Spring washer in the screw industry, often known as cushion. Its material is stainless steel and carbon steel, carbon steel is also iron. Generally used spring washer specifications are M3, M4, M5, M6, M8, M10.M12, M14, M16. These specifications are more commonly used. Spring washer national standard GB/T 94.1-87, which stipulate the Specification of spring washer is 2-48mm.