Heli-coil A3585-04CNPF224 Screw-locking Insert 4-40 Unc

Product Description

The HELI-COIL A3585-04CNPF224 is a tangless, screw-locking helical coil insert designed to create strong, vibration-resistant threaded holes in parent materials. Built from Grade 304 stainless steel with a primer-free finish, it accepts a 4-40 UNC screw thread and delivers consistent locking performance through a deformed coil section that grips the mating fastener. The overall insert length is 0.224 inches with a 2D length-to-diameter ratio, making it suited for applications where thread depth is limited. A maximum locking torque of 48 oz-in and a minimum breakaway torque of 10 oz-in define its holding performance. Maintenance and assembly technicians across aerospace, industrial, and precision equipment applications install these inserts to restore or reinforce stripped or soft-material threads.

This insert is used wherever a 4-40 UNC threaded hole needs permanent locking reinforcement in metal, composite, or high-wear assemblies. The tangless design eliminates the need for tang removal after installation, reducing the risk of loose tang fragments inside housings or enclosures. It is particularly common in precision equipment, electronics enclosures, and instrument panels where small fastener sizes and clean internal clearances are critical. A single insert is included per package, with a minimum order quantity of 10 pieces, making it appropriate for both repair and production line use.

Key Features

• Tangless design eliminates post-installation tang removal and prevents loose debris inside assemblies
• Grade 304 stainless steel construction provides corrosion resistance in demanding environments
• Primer-free finish for clean, ready-to-install use without additional surface prep
• Maximum locking torque of 48 oz-in with a minimum breakaway torque of 10 oz-in
• 0.224-inch overall length with 2D length-to-diameter ratio suits shallow thread engagement applications
• 6-3/4 free coils provide consistent thread engagement along the insert body

Compatibility

Designed as an OEM-style screw-locking insert for 4-40 UNC threaded applications requiring a tangless, 2D-length helical coil insert in Grade 304 stainless steel.

Installation Notes

Installation requires a properly sized Heli-Coil or compatible tangless insert tool and a correctly prepared, tapped hole using the appropriate STI (Screw Thread Insert) tap for 4-40 UNC. Ensure the parent material is securely fixtured and the hole is clean and free of debris before driving the insert. Power down any equipment and relieve all system pressure before performing thread repair on live assemblies. Follow the fastener manufacturer's installation torque guidelines and applicable industry standards for the specific application.