E-z Lok 303-428 Thread Locking Insert 1/4-28 Unf Stainless

Product Description

The E-Z LOK 303-428 is a self-locking threaded insert manufactured from 303-grade stainless steel with a bright finish. It accepts a 1/4-28 UNF internal thread (Class 2B fit) and installs via a 7/16-14 external thread (Class 2A fit) driven into a standard tapped hole. Overall length is 7/16 inches (0.437 inches). The self-lock wall design provides a secure, vibration-resistant thread engagement in parent materials where thread stripping or pullout is a concern. Machinists, maintenance technicians, and assembly professionals install this type of insert to restore or reinforce threads in metal components.

This insert is suited for applications requiring a corrosion-resistant internal thread in assemblies exposed to moisture, mild chemicals, or outdoor environments. The 1/4-28 UNF thread specification makes it appropriate for fine-thread fastener applications in precision mechanical, industrial, and maintenance repair scenarios. It installs into a standard tapped hole sized for the 7/16-14 external thread, requiring no special installation tool beyond standard tap tooling.

Key Features

• Self-lock wall design resists loosening under vibration and dynamic loads
• 303 stainless steel construction provides corrosion resistance in wet or chemical environments
• 1/4-28 UNF internal thread (Class 2B) for fine-thread fastener compatibility
• 7/16-14 external thread (Class 2A) installs into a standard tapped hole
• Compact 7/16-inch overall length suits thin-wall and space-constrained assemblies
• Bright finish with no additional coating that could affect thread tolerances

Compatibility

Designed as an OEM-style thread repair and reinforcement insert for metal parent materials tapped to accept a 7/16-14 external thread with a standard tap, yielding a 1/4-28 UNF internal fastener thread.

Installation Notes

Installation is performed by machinists or mechanical technicians using standard hand or machine tapping equipment. The parent material must be drilled and tapped to the correct 7/16-14 minor diameter before insert installation. De-energize and lock out any equipment before servicing threaded connections in powered assemblies. Do not exceed the torque capacity of the 1/4-28 internal thread during final fastener installation, and verify thread engagement depth meets the requirements of the application.