Carbon Steel Coil Spring 1) Material: 62Si2MnA, 65Mn, SK3,SK4, ... 3-80mmOur company are a professional manufacturer specialized in producing all classes of springs for Industrial machine,( ... electrical machine ,start-up machine,etc.),constant force spring for door ,windows ,electric fans ,machines of lift ... machine, fan, oven,etc...).And are specialized in producing springs for various kinds of carbon and ...