UNF Inserts - Free Running

In the free state they are greater in diameter than the tapped hole into which they are installed. In the assembly operation the torque applied to the tang reduces the diameter of the leading coil and permits it to enter the tapped thread. When the torque or rotation is stopped, the coils expand with a spring-like action anchoring the insert permanently in place against the tapped hole. No staking, locking, swaging, keying, nor interference fit is required to retain Heli-Coil® Inserts, thereby eliminating stress concentration in the parent material. The Heli-Coil® Insert automatically adjusts itself, radially and axially, to any expansion or contraction of the parent material.