Heli-coil A3585-5CN625 Screw-locking Insert 5/16-18 Unc

Product Description

The HELI-COIL A3585-5CN625 is a tangless screw-locking helical coil insert designed to create a strong, vibration-resistant threaded connection in tapped holes. Built from Grade 304 stainless steel with a bright finish, it accepts a 5/16-18 UNC thread and measures 0.625 inches in overall length, giving a 2D length-to-diameter ratio. The locking design uses a deformed coil to resist fastener back-out under load or vibration. Machinists, maintenance technicians, and MRO professionals install these inserts to restore or reinforce stripped threads and to upgrade thread strength in softer base materials such as aluminum, cast iron, and plastic.

This insert is suited for applications where thread locking without chemical threadlockers is preferred, including aerospace assemblies, industrial equipment, and mechanical sub-assemblies subject to vibration or repeated disassembly. The tangless design eliminates the tang-removal step required with standard helical inserts, making installation faster and reducing the risk of leaving tang fragments in blind holes. It is appropriate for both production and field repair work across manufacturing, maintenance, and equipment overhaul environments.

Key Features

• Tangless design eliminates tang-removal step, reducing installation time and debris risk in blind holes
• Grade 304 stainless steel construction provides corrosion resistance in wet or chemically exposed environments
• Maximum locking torque of 60 in/lb with a minimum break-away torque of 7.50 in/lb for secure fastener retention
• 5/16-18 UNC thread size with a 2D length-to-diameter ratio for a balanced grip-to-depth profile
• Outside diameter range of 0.380 to 0.400 inches for consistent interference fit in the tapped hole
• Bright finish on 304 stainless for clean appearance and dimensional consistency

Compatibility

Designed as an OEM-style replacement or new-installation screw-locking insert for tapped holes requiring a 5/16-18 UNC thread form with a 2D insert length.

Installation Notes

Installation requires a correctly sized HELI-COIL tap to prepare the parent material hole before insert placement; standard UNC taps will not produce the correct hole geometry. A compatible tangless installation tool is required to drive the insert to the proper seated depth. Always power down or de-energize any assembly before performing thread repair or insert installation near live components. Follow the fastener manufacturer torque specifications for the finished assembly after insert seating.