Heli-Coil® Standard and Screw-Lock Inserts are the original — and have an extensive background of tension, torque, shear, vibration and fatigue tests conducted by the American industry's leading companies as well as the U.S. Military.

Successful applications in the fields of aviation, electronics, industrial, automotive and military equipment provide a wealth of experience and confidence in the performance and reliability of Heli-Coil® Inserts.

Standard and Screw-Lock inserts come in Metric Coarse, Metric Fine, UNC and UNF varieties.

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.

Screw Lock

The HELI-COIL SCREW-LOCK INSERT provides an exclusive, resilient internal locking thread that grips the bolt and prevents it from loosening under vibration or impact.

Locking action is achieved by one or more of the coils of the Insert having a series of straight segments, or chords. When the bolt enters this grip coil these chordal segments flex outward creating pressure on the bolt. This pressure is exerted between the flanks of the bolt thread thus utilizing the maximum contact area and minimizing the unit pressure.

HELI -COIL SCREW-LOCK INSERTS permit repeated assembly and disassembly, yet will not relax their grip on the screw even in tough metals such as cast iron, alloy steel, titanium, etc.

Characteristics

• Screw-Lock Inserts positively secure threaded members against loosening caused by vibration and shock. They have a high reusable factor due to the exclusive HELI-COIL Resilient Screw-Lock which permits frequent removal and reassembly of bolt without appreciable, loss of torque.

• Positive self-locking torque, complying with MIL-I-8846 & MIL-N-25027.

• Savings in space, weight and money, through the elimination of lock wiring, lock nuts, lock washers, chemical compounds, plastic pellets/patches and other locking mechanisms.

In addition Screw-Lock Screw Thread Inserts have all the characteristics of Free Running Inserts.