Helicoil #4 - 40 3xD Screw-Lock Thread Repair Insert

Thread insert is precision formed screw thread coils worked into a diamond shape. The resultant surface finish is a mirror-like 8-16 micro inches. This wire is then wound into a spiral coil which when installed into Heli-Coil tapped holes, provides permanent conventional 60° internal screw threads. This assembled insert accommodates any standard bolt or screw (MIL-S-7742) and MIL-S8879 (UNJ controlled radius root) male threaded members. Heli-Coil inserts are larger in diameter before installation than the tapped hole. During installation the inserting tool applies torque to the tang reducing the diameter of the leading coil permitting it to enter the tapped thread. After installation each high tensile stainless steel coil of the insert expands outward with a spring like action permanently anchoring the insert.