Heli-coil A3591-3CN285 10-32 Unf Locking Insert 1-1/2D Ss

Product Description

The HELI-COIL A3591-3CN285 is a screw-locking wire thread insert designed to create durable, vibration-resistant internal threads in tapped holes. Manufactured from Grade 304 stainless steel with a bright finish, this tangless insert measures 0.285 inches in overall length and accommodates a 10-32 UNF thread with a 1-1/2D length-to-diameter ratio. The locking design uses a deformed coil section to provide positive prevailing torque, preventing fastener back-out under load, vibration, or thermal cycling. It is installed and removed without the need for a tang break-off tool, reducing debris risk in blind holes. Maintenance technicians, aerospace assemblers, and industrial mechanics install these inserts during thread repair or original assembly work.

This insert is suited for applications where a standard internal thread must be reinforced or repaired in metallic or high-strength base materials. The 10-32 UNF thread size is common in precision mechanical assemblies, electrical enclosures, instrumentation panels, and light structural components. The 1-1/2D engagement length provides a reliable torque transfer in thin-section parts or where hole depth is limited. The Grade 304 stainless steel construction resists corrosion in moderate chemical and moisture environments, making it a practical choice for outdoor equipment, marine-adjacent assemblies, and process equipment.

Key Features

• Grade 304 stainless steel construction for corrosion resistance in demanding service environments
• Tangless design eliminates tang removal after installation and prevents debris in blind-hole applications
• Maximum locking torque of 13 in/lb provides positive fastener retention under vibration
• Minimum break-away torque of 2.00 oz-in ensures controlled re-entry without seizing
• 0.285 inches overall length with 1-1/2D ratio suits limited-depth tapped holes
• 6-7/8 free coils deliver consistent thread engagement across the insert length

Compatibility

Designed as an OEM-style screw-locking insert for tapped holes requiring 10-32 UNF internal threads in metallic base materials.

Installation Notes

Installation requires a properly tapped hole prepared with the appropriate HELI-COIL tap to achieve the correct pre-thread diameter for the insert outside diameter range of 0.236 to 0.256 inches. Use the corresponding tangless installation tool to drive the insert to the specified depth without overtightening. Power down or de-energize any assembly before performing thread repair work in live panels or enclosures. Follow the applicable equipment manufacturer torque specifications when reinstalling fasteners into the finished insert.