Heli-coil A3585-5CN312 5/16-18 Unc Screw-locking Insert

Product Description

The HELI-COIL A3585-5CN312 is a tangless screw-locking helical insert designed to create strong, vibration-resistant threaded connections in parent material that has been tapped to accept a wire thread insert. Manufactured from Grade 304 stainless steel with a bright finish, this insert installs into a prepared UNC-tapped hole and provides a locking function that resists fastener back-out under dynamic loads. The 5/16-18 UNC thread size and 1D length-to-diameter ratio make it a compact, reliable solution. Maximum locking torque is 60 in/lb, with a minimum breakaway torque of 7.50 in/lb. It is installed by licensed machinists, maintenance technicians, and field service professionals working in metal repair and thread restoration applications.

This insert is suited for use in aluminum, cast iron, magnesium, and other materials where thread stripping is a concern or where a damaged thread needs restoration. The tangless design eliminates the need for a tang removal step after installation, streamlining the installation process. With an overall length of 0.312 inches and an outside diameter range of 0.380 to 0.400 inches, it fits standard HELI-COIL tapped holes for this thread size. Typical applications include aerospace assemblies, industrial equipment, and heavy-duty mechanical maintenance where fastener retention under vibration is critical.

Key Features

• Grade 304 stainless steel construction for corrosion resistance in demanding environments
• Tangless design eliminates the tang removal step after installation
• 5/16-18 UNC thread form with 1D length-to-diameter ratio
• Maximum locking torque of 60 in/lb with minimum breakaway torque of 7.50 in/lb
• Bright finish on stainless steel base material
• Four free coils provide consistent locking engagement

Compatibility

Designed for use in standard HELI-COIL tapped holes sized for 5/16-18 UNC tangless screw-locking inserts. Requires a compatible HELI-COIL installation tool and properly prepared parent material tapped to the correct insert thread specification.

Installation Notes

Installation requires a properly tapped hole using the correct HELI-COIL tap for the 5/16-18 UNC insert size. Power down or de-energize any equipment before accessing fastened assemblies. Use the appropriate tangless installation tool to drive the insert to the correct depth without damaging the coil or parent material threads. Do not attempt installation without the correct tooling, as improper installation can damage the insert or the tapped hole.