Heli-coil A1185-04CNPF112 4-40 Unc Free Running Insert

Product Description

The HELI-COIL A1185-04CNPF112 is a free running wire thread insert designed to create strong, wear-resistant internal threads in tapped holes. Sized for 4-40 UNC threading with an overall length of 0.112 inches, this insert is manufactured from 304 stainless steel with a primer-free finish. The tanged design allows for installation using a standard HELI-COIL installation tool, which drives the insert into the prepared tapped hole. This insert is used by machinists, assembly technicians, and maintenance professionals to repair stripped threads or to reinforce threads in soft base materials such as aluminum, magnesium, and plastics.

This insert is suited for light-duty fastener applications where a 4-40 UNC thread form is required. The 1D length-to-diameter ratio makes it appropriate for shallow boss or thin-wall installations where thread engagement depth is limited. With 2-3/4 free coils, the insert provides consistent spring-back and secure seating after installation. Common applications include electronic enclosures, instrument panels, and precision assemblies in aerospace, industrial, and commercial equipment maintenance.

Key Features

• 4-40 UNC thread size for compatibility with standard inch-series fasteners
• 304 stainless steel construction provides corrosion resistance and durability
• Primer-free finish allows for direct installation without surface prep coatings
• Tanged design works with standard HELI-COIL installation tooling
• 1D length-to-diameter ratio suits shallow or thin-wall thread repair applications
• 2-3/4 free coils deliver consistent radial pressure and thread locking behavior

Compatibility

Designed as an OEM-style free running insert for use in any application requiring a 4-40 UNC thread form in a pre-tapped HELI-COIL or equivalent STI (Screw Thread Insert) hole.

Installation Notes

Installation requires a properly prepared STI tap and a matching HELI-COIL installation tool for the 4-40 thread size. Ensure the tapped hole is clean and free of debris before inserting. After the insert is seated flush or just below the surface, remove the tang using a tang break-off tool. Follow applicable torque specifications for the fastener assembly as defined by the equipment manufacturer or applicable engineering standards.