Heli-coil A1185-4CN750 Free Running Insert 1/4-20 Unc

Product Description

The HELI-COIL A1185-4CN750 is a free running helical wire thread insert designed to create strong, wear-resistant internal threads in tapped holes. Built from 304 stainless steel with a bright, uncoated finish, this insert accepts a 1/4-20 UNC male thread and measures 0.75 inches in overall length, representing a 3D length-to-diameter ratio. The tanged design allows installation with a standard HELI-COIL installation tool. Machinists, maintenance technicians, and assembly professionals install these inserts to repair stripped threads or build durable threaded features into softer base materials such as aluminum, magnesium, or plastics.

This insert is well suited for light industrial assembly, field thread repair, and OEM manufacturing applications where a 1/4-20 UNC thread must withstand repeated fastener engagement. The 304 stainless steel construction resists corrosion, making it appropriate for environments with moisture exposure or chemical contact. With 12-3/4 free coils, the insert distributes load evenly along the full thread engagement length. Each order contains one insert; minimum order quantity is 10 pieces.

Key Features

• 1/4-20 UNC thread size for broad fastener compatibility
• 0.75 inch overall length with a 3D length-to-diameter ratio for full thread engagement
• 304 stainless steel construction for corrosion resistance
• Tanged design for positive installation tool engagement and controlled placement
• 12-3/4 free coils for even load distribution across the thread interface
• Bright, uncoated finish - no coating thickness to account for in hole sizing

Compatibility

Designed as an OEM-style and repair replacement thread insert for any tapped hole requiring a 1/4-20 UNC internal thread, provided the hole is prepared to HELI-COIL specified tap drill size for this series.

Installation Notes

A licensed machinist or qualified technician should prepare the parent hole using the correct HELI-COIL tap drill size and the designated tapping tool before installation. Use the appropriate HELI-COIL installation tool for tanged inserts to drive the insert to the correct depth. After installation, break off the drive tang using a tang break-off tool or punch; do not leave the tang in a blind hole where it may become a foreign object. Follow all applicable workplace safety and torque practices for the fastener assembly.