I: Standard thickness of disc spring t <1.25mm, punching, cold forming, to the acute angle
II: 1 25 ≤ thickness t ≤ 6mm, punching, cold forming, inner and outer diameter to an acute angle or a precise punching process, cold forming, to the acute angle
III: 6 ≤ thickness t ≤ 16mm, casting and forging embryo, the whole process to the surface an acute angle punching, cold forming, machining to an acute angle within the outer diameter or fine punching, cold forming, to an acute angle.