Heli-coil AT1185-04C168 4-40 Unc Free Running Insert

Product Description

The HELI-COIL AT1185-04C168 is a free running wire thread insert designed to create strong, wear-resistant internal threads in tapped holes. This tangless, helical coil insert is manufactured from 304 stainless steel with a bright, uncoated finish. It accepts a 4-40 UNC thread and measures 0.168 inches in overall length, giving it a 1-1/2D length-to-diameter ratio. With 4-3/4 free coils, it provides reliable thread engagement in base materials prone to stripping or damage. Machinists, maintenance technicians, and assembly professionals install these inserts to restore or upgrade thread integrity in metal, plastic, or composite workpieces.

This insert is suited for light-duty fastening applications that require a 4-40 UNC thread form, including precision instrument assembly, electronics enclosures, and small mechanical component repair. The tangless design eliminates the need for a tang break-off step after installation, which speeds up production line workflows and reduces the risk of loose tangs contaminating assemblies. It is commonly used in aerospace, industrial, and general manufacturing environments where thread strength and corrosion resistance are required in tight spaces.

Key Features

• 4-40 UNC thread size for compatibility with standard inch-series fasteners
• Tangless design eliminates post-installation tang removal
• 304 stainless steel construction provides corrosion resistance
• 0.168 inch overall length with 1-1/2D length-to-diameter ratio
• 4-3/4 free coils for consistent thread engagement
• Bright, uncoated finish maintains dimensional accuracy

Compatibility

Designed as an OEM-style free running thread insert for tapped holes requiring a 4-40 UNC internal thread form in metal or composite base materials.

Installation Notes

Installation requires a properly sized HELI-COIL tap and the appropriate tangless insert tool for the 4-40 thread size. Power down or de-energize any equipment before performing thread repair on assembled components. Follow the insert manufacturer's installation tooling specifications to ensure proper seating depth and coil engagement. Tangless inserts do not require a tang extraction step, but the finished hole should be inspected for full thread engagement before torquing fasteners.