Heli-coil A3585-4CNW250 Screw-locking Insert 1/4-20 Unc

Product Description

The HELI-COIL A3585-4CNW250 is a tangless screw-locking helical insert designed to create durable, vibration-resistant threaded connections in parent materials that require added thread strength. Manufactured from Grade 304 stainless steel with a dry film lubricant finish, this insert measures 0.25 inches in overall length and is sized for 1/4-20 UNC thread applications. The tangless design eliminates the need for tang break-off after installation, reducing installation time and preventing loose metal debris inside assemblies. With a maximum locking torque of 30 inch-pounds and a minimum breakaway torque of 4.50 inch-pounds, it provides reliable thread locking without the need for chemical thread-locking compounds. Machinists, maintenance technicians, and assembly professionals working in corrosion-sensitive environments are the primary installers.

This insert is suited for use in aerospace, industrial, and general mechanical assemblies where a 1/4-20 UNC threaded hole requires reinforcement or repair. The 1D length-to-diameter ratio and 0.25-inch overall length make it appropriate for applications where material thickness is limited. The Grade 304 stainless steel construction makes it a practical choice in environments subject to moisture, chemicals, or moderate heat. It is used in both OEM production and field repair scenarios where maintaining precise thread engagement and locking characteristics is critical.

Key Features

• Tangless design eliminates tang removal and prevents debris contamination in assemblies
• Grade 304 stainless steel construction provides corrosion resistance in demanding environments
• Dry film lubricant finish aids installation and reduces galling during thread engagement
• Maximum locking torque of 30 inch-pounds for secure, vibration-resistant thread locking
• Minimum breakaway torque of 4.50 inch-pounds ensures consistent locking performance
• 1/4-20 UNC thread standard with 1D length-to-diameter ratio for shallow-material applications

Compatibility

Designed for installation into tapped holes prepared to 1/4-20 UNC thread specifications, with an outside diameter range of 0.3100 to 0.3300 inches to suit the corresponding STI (Screw Thread Insert) tap size.

Installation Notes

Installation requires a correctly sized STI tap to prepare the parent material hole and a tangless insert installation tool matched to the 1/4-20 UNC thread size. Power down or de-energize any equipment before accessing threaded connection points in live assemblies. The tangless design does not require a tang break-off step, but verify that the insert is fully seated flush with or below the parent material surface before fastener installation. Follow applicable manufacturer torque specifications for the mating fastener after insert installation.