Heli-coil A1185-4CNPF250 Free Running Insert 1/4-20

Product Description

The HELI-COIL A1185-4CNPF250 is a free running helical wire threaded insert designed to create or restore strong, durable internal threads in parent material. With a 1/4-20 UNC thread size and an overall length of 0.25 inches, this insert is classified as a 1D length-to-diameter ratio configuration. It is constructed from 304 stainless steel with a primer-free finish, making it well suited for applications where corrosion resistance and clean installation are required. Machinists, maintenance technicians, and assembly professionals install this type of insert when original threads are stripped, weak, or need reinforcement in softer base materials.

This insert is used in light industrial, mechanical assembly, and maintenance repair operations where 1/4-20 UNC threaded holes must meet load or torque requirements that the parent material alone cannot sustain. The tanged design works with standard Heli-Coil installation tooling. Common install scenarios include thread repair in aluminum housings, castings, and structural components across HVAC equipment, machinery, and general mechanical assemblies. The primer-free finish allows immediate use without additional surface preparation steps.

Key Features

• 1/4-20 UNC thread size for compatibility with standard unified coarse fastener systems
• 0.25 inch overall length with 1D length-to-diameter ratio for shallow-hole applications
• 304 stainless steel construction for corrosion resistance in demanding environments
• Tanged design compatible with standard free running insert installation tools
• Primer-free finish allows direct installation without additional prep
• 3-3/8 free coils for consistent thread engagement across the insert length

Compatibility

Designed as an OEM-style thread repair and thread reinforcement insert for use in any parent material with a prepared 1/4-20 UNC Heli-Coil tapped hole using the appropriate drill and tap specification for free running inserts.

Installation Notes

Installation requires a licensed machinist or qualified mechanical technician using the correct Heli-Coil tap and installation tool sized for the 1/4-20 free running insert series. The parent material must be drilled and tapped to the specified Heli-Coil tap drill size before insert installation. Power down or de-energize any equipment before performing thread repair on active assemblies. After installation, the tang must be removed using an approved tang break-off tool; do not use pliers or improvised tools that could damage the newly installed coil.