Steel thread insert is a new type of fasterner. It is precision formed coils of stainless steel wire having a diamond shaped crossed-section. There sre two forms:free-run type and screw-locking type. Screw-locking type offers a screw-lock effect by polygon elastic safety coils.Thread insert is used for manufacturing high strength, wear-resistant, high duty, vibration-proof in merallic and non-metallic materials such as Al, Mg alloy, plastic to form M and MJ thread. Now the insert technology has been widely used in many industries such as aerospace, aviation, electricity, instrument, chemical fiber and so on.