Heli-coil A1185-04EN168 Free Running Insert 4-40 Unc

Product Description

The HELI-COIL A1185-04EN168 is a free running helical wire thread insert designed to restore or reinforce internal threads in drilled and tapped holes. Sized for 4-40 UNC thread applications, this insert measures 0.168 inches overall length and is manufactured from 18-8 stainless steel, providing corrosion resistance in demanding environments. The tanged design allows for easy installation using a standard HELI-COIL installation tool. The 1-1/2D length-to-diameter ratio and 4-3/4 free coils deliver reliable thread engagement for light fastener loads typical in instrumentation, electronics, and precision mechanical assemblies. Machinists, maintenance technicians, and field service professionals install this type of insert when parent material threads are stripped or when thread durability needs to be improved.

This insert is suited for use in metals, plastics, and composite materials where a 4-40 UNC internal thread is required. Common applications include electronic enclosures, instrument panels, and small-diameter fastener repairs in aerospace, industrial, and commercial equipment. The free running design allows standard fasteners to engage and thread through without interference or preload, making it a straightforward drop-in thread repair or reinforcement solution.

Key Features

• 4-40 UNC thread size for use with standard 4-40 fasteners
• 0.168 inch overall length at 1-1/2D length-to-diameter ratio
• 18-8 stainless steel construction for corrosion resistance
• Tanged design for precise installation with standard installation tooling
• 4-3/4 free coils for consistent thread engagement and load distribution
• Free running configuration accepts standard fasteners without interference

Compatibility

Designed as an OEM-style thread repair insert for any parent material tapped to accept a 4-40 UNC helical insert. Verify correct tap drill and insert installation tool for the 4-40 HELI-COIL insert series before installation.

Installation Notes

Installation requires a HELI-COIL series tap, an installation mandrel or tool, and a tang break-off tool for tanged insert types. The parent hole must be drilled and tapped to the correct HELI-COIL oversize specification before the insert is driven. Remove all chips from the hole before inserting. After seating the insert flush or slightly below the surface, break off the tang using the appropriate tool or needle-nose pliers.