The 80 -level chain is made of steel wires as raw materials, and the drawing → editing chain → welding → seven -ring correction → heat treatment → 1 meter correction → tension test → surface treatment is combined to make the standard chain. Good quality chains generally use mid -frequency resistance to welding, and the strength and toughness of the chain will be better. Full automatic equipment in chain production> semi -automatic equipment> manual welding. Good equipment and mature technical operations are essential when making chain production. The equipment needs to be maintained regularly. For a long time, the device needs to be replaced if the chain is not reached.