Heli-coil A3591-3CNW285 Screw-locking Insert 10-32 Unf

Product Description

The HELI-COIL A3591-3CNW285 is a tangless screw-locking helical coil insert designed to create durable, vibration-resistant internal threads in parent materials with stripped, damaged, or undersized thread bores. Manufactured from Grade 304 stainless steel with a dry film lubricant finish, this insert accepts a 10-32 UNF thread and provides a 1-1/2D length-to-diameter ratio. The overall installed length is 0.285 inches, with a coil count of 6-7/8 free coils. The locking feature delivers a maximum locking torque of 13 inch-pounds and a minimum breakaway torque of 2 inch-pounds, providing controlled thread engagement without permanent seizure. Installation and removal do not require a tang break-off step, reducing debris risk in blind-hole applications.

This insert is suited for aerospace, precision machining, electronics assembly, HVAC equipment manufacturing, and general mechanical repair applications where a reliable 10-32 UNF internal thread is required in aluminum, magnesium, cast iron, plastics, or other base materials prone to thread wear. The stainless steel construction and dry film lubricant coating make it appropriate for environments with moderate corrosion exposure or where galling resistance is a priority. Machinists, assembly technicians, and field service mechanics working on small-fastener thread repair or thread reinforcement applications are the primary installers.

Key Features

• Tangless design eliminates tang removal step, reducing installation time and contamination risk in blind holes
• Grade 304 stainless steel construction provides corrosion resistance and long service life
• Dry film lubricant finish reduces galling and supports consistent torque performance during installation
• Maximum locking torque of 13 inch-pounds with minimum breakaway torque of 2 inch-pounds for controlled thread locking
• 6-7/8 free coils across a 0.285-inch overall length for full thread engagement in thin parent material sections

Compatibility

Designed as an OEM-style replacement or thread repair insert for parent materials tapped to accept a 10-32 UNF helical coil insert with an outside diameter range of 0.236 to 0.256 inches.

Installation Notes

Installation requires a HELI-COIL compatible tang-free installation tool sized for 10-32 UNF inserts; confirm the parent bore has been drilled and tapped to the correct insert tap size before installation. De-energize or depressurize any assembly before performing thread repair on components under electrical or mechanical load. Follow the insert manufacturer's installation torque guidelines and applicable shop or field service procedures. Do not attempt to install with standard tap tools not designed for helical coil inserts, as improper installation can damage the coil or parent thread.