Heli-coil 3591-3CN285S Screw-locking Insert 10-32 Unf

Product Description

The HELI-COIL 3591-3CN285S is a screw-locking helical coil insert designed to create a secure, vibration-resistant internal thread in a parent material. The insert uses a tanged installation style and holds a 10-32 UNF thread standard. Manufactured from Grade 304 stainless steel, it delivers corrosion resistance suitable for demanding service environments. The overall length is 0.285 inches at a 1-1/2D length-to-diameter ratio. Maximum locking torque is 13 inch-pounds, with a minimum breakaway torque of 2 inch-ounces. This type of insert is installed by licensed mechanics, maintenance technicians, and precision assembly trades working in metal fabrication, HVAC equipment repair, and industrial equipment service.

This insert is suited for applications where a stripped, worn, or undersized 10-32 UNF threaded hole must be restored or reinforced in aluminum, cast iron, magnesium, or other base materials. The locking feature resists loosening under vibration and thermal cycling, making it appropriate for equipment panels, compressor housings, motor mounts, and similar high-cycle assemblies. It is typically installed using a dedicated HELI-COIL installation tool matched to the 10-32 thread size.

Key Features

• 10-32 UNF internal thread for precision fastener engagement
• Grade 304 stainless steel construction for corrosion resistance
• Tanged design for controlled installation depth
• 1-1/2D length-to-diameter ratio at 0.285 inches overall length
• Maximum locking torque of 13 inch-pounds resists vibration-induced loosening
• Outside diameter range of 0.236 to 0.256 inches for consistent fit in tapped holes

Compatibility

Designed as an OEM-style replacement or new-installation insert for parent materials tapped to accept a 10-32 UNF helical coil insert with a 1-1/2D engagement length.

Installation Notes

Installation requires a properly tapped hole sized for the insert outside diameter range and a compatible HELI-COIL insertion tool. Power down and de-energize any equipment before threading or reworking fastener holes in electrical or mechanical assemblies. After installation, break off the drive tang using a tang break-off tool; confirm tang removal before reassembly. Follow the fastener torque specifications of the host equipment manufacturer, not the insert locking torque value alone.