According to the nature of the force, the spring can be divided into tensile springs, compression springs, torsion springs and bending springs, according to the shape can be divided into disc spring, ring spring, plate spring, helical spring, truncated vortex coil spring and torsion bar spring, according to the production process can be divided into cold coil spring and hot coil spring. The ordinary cylinder spring is simple in manufacture and can be made into various types according to the loading situation, and the structure is simple, so it is widely used. Spring manufacturing materials should generally have high elastic limit, fatigue limit, impact toughness and good heat treatment properties, commonly used carbon spring steel, alloy spring steel, stainless steel spring and copper alloy, nickel alloy and rubber. The method of manufacturing spring is cold coil method and hot coil method. Spring wire diameter less than 8 mm of the general cold roll method, greater than 8 mm with the heat coil method. Some springs after being made also need to carry on the pressure or the shot peening treatment, may raise the spring the load capacity.