Heli-Coil inserts provide a positive means for protecting and strengthening tapped threads in any material. Commonly used in OEM design, the unique design features of the insert offer many benefits.
Heli-Coil offers maximum design flexibility while adhering to conservative engineering practice, allowing use of Heli-Coil inserts in virtually any application.
Five lengths of inserts are available. In the Heli-Coil catalog (HC2000), the lengths are listed as multiples of the nominal thread diameter of the screw; 1, 1-1/2, 2, 2-1/2, and 3.
This choice of insert length balances the bolt tensile strength against the shear strength of the parent material. This allows for the design of assemblies where the bolt will fail before the parent material.
Assembly strength is a function of shear area and the shear strength of both the bolt and parent material.
For detailed charts on specific load values, Heli-Coil Technical Bulletin 68-2 (inch) covers the complete range of sizes, parent materials and bolt strengths.
The effect of corrosion on threaded assemblies is dependent on many factors:
The following recommendations apply for minimizing the effects of corrosion on Heli-Coil stainless steel insert assemblies at operating temperatures less than 800°F, using carbon steel or alloy steel bolts.
The following definitions apply: