Heli-coil A3585-5CN781 Screw-locking Insert 5/16-18 Unc

Product Description

The HELI-COIL A3585-5CN781 is a tangless screw-locking helical coil insert designed to provide vibration-resistant thread reinforcement in threaded assemblies. Manufactured from Grade 304 stainless steel with a bright finish, this insert accepts a 5/16-18 UNC thread and measures 0.781 inches overall length, corresponding to a 2-1/2D length-to-diameter ratio. It delivers a maximum locking torque of 60 in/lb and a minimum breakaway torque of 7.50 in/lb. The tangless design eliminates the need for tang removal after installation, reducing assembly time and the risk of loose fragments in the assembly. It is installed by licensed machine technicians, maintenance professionals, and precision assembly workers.

This insert is suited for applications requiring durable thread repair or thread reinforcement in stainless-compatible parent materials. The 5/16-18 UNC thread form fits standard unified coarse-thread fastener systems common in industrial, aerospace-adjacent, and general mechanical assemblies. The 11-7/8 free coils and the locking feature make it appropriate for joints subject to vibration or repeated fastener removal. Sold individually with a minimum order quantity of 5 units.

Key Features

• Tangless design eliminates post-installation tang removal step
• Grade 304 stainless steel construction resists corrosion in wet or chemically active environments
• Maximum locking torque of 60 in/lb provides secure vibration-resistant thread engagement
• Minimum breakaway torque of 7.50 in/lb ensures positive locking action is maintained
• 0.781 inches overall length at 2-1/2D ratio suits deeper thread engagement requirements
• Bright finish with 11-7/8 free coils for consistent coil engagement across the full insert length

Compatibility

Designed as an OEM-style screw-locking helical coil insert for 5/16-18 UNC threaded applications requiring a 2-1/2D length insert in stainless steel parent material or compatible alloys.

Installation Notes

Installation requires a proper HELI-COIL or compatible tangless insert installation tool sized for 5/16-18 UNC thread. The parent material bore must be drilled and tapped to the correct insert tap size before installation. Ensure the assembly is de-energized and secured before performing thread repair on any mechanical or electrical component. Do not attempt installation without the correct driving tool, as improper installation can damage the insert coils or the parent thread.