Heli-coil A3585-4CN625 Screw-locking Insert 1/4-20 Unc

Product Description

The HELI-COIL A3585-4CN625 is a tangless, screw-locking wire thread insert designed to restore or reinforce internal threads in metal assemblies. Made from Grade 304 stainless steel with a bright finish, it installs into a pre-tapped host bore and provides a hardened, corrosion-resistant thread form that resists fastener back-out under vibration. The insert carries a 1/4-20 UNC thread size, measures 0.625 inches in overall length at a 2-1/2D length-to-diameter ratio, and delivers a maximum locking torque of 30 in/lb with a minimum breakaway torque of 4.50 in/lb. Typically installed by maintenance technicians, machinists, and assembly mechanics in production and repair environments.

This insert is suited for applications where thread stripping, cross-threading, or material fatigue has compromised the host bore, or where original design calls for a hardened thread insert in aluminum, cast iron, or soft metal parent materials. The tangless design eliminates the need to remove a drive tang after installation, reducing installation steps and the risk of tang fragments in enclosed assemblies. Common in aerospace, automotive, industrial equipment, and general mechanical repair scenarios where 1/4-20 UNC fasteners are used under vibration or repeated removal cycles.

Key Features

• Tangless design eliminates post-installation tang removal and prevents loose fragments in blind holes
• Grade 304 stainless steel construction for corrosion resistance in demanding service environments
• 1/4-20 UNC thread form matches standard inch fasteners
• 2-1/2D length-to-diameter ratio at 0.625 inches OAL for a deeper thread engagement zone
• Maximum locking torque of 30 in/lb resists fastener loosening under vibration
• Minimum breakaway torque of 4.50 in/lb maintains removability without thread damage
• Bright finish with 10-3/8 free coils for consistent coil tension and seating

Compatibility

Designed as an OEM-style thread repair and reinforcement insert for host materials tapped to accept 1/4-20 UNC Heli-Coil inserts at a 2-1/2D installation depth.

Installation Notes

Installation requires a properly sized Heli-Coil tap to prepare the host bore before the insert is driven. Power down or de-energize any assembly before thread repair work begins. Use the appropriate tangless installation tool specified for this insert series to avoid coil distortion. Verify host material and bore depth are within specification before installation to ensure full thread engagement.