E-z Lok FL-428-HI Brass Threaded Insert 1/4-28 Unf

Product Description

The E-Z LOK FL-428-HI is a brass headed threaded insert designed for heat installation into thermoplastic materials. The insert accepts a 1/4-28 UNF internal thread and provides a durable, load-bearing metallic thread in assemblies where plastic alone cannot withstand fastener torque or repeated disassembly. The insert measures 0.341 inches in diameter with an overall length of 0.553 inches. The flanged head, measuring 0.375 inches in diameter and 0.05 inches high, seats flush against the surface after installation and prevents the insert from pulling through the host material. Installation is performed using a soldering iron or dedicated heat-set press tool.

This insert is used in plastic enclosures, electronic housings, injection-molded components, and light-duty structural plastic assemblies across HVAC, electrical, and general manufacturing applications. The heat installation method allows the brass insert to be pressed into a pre-drilled or molded pilot hole as the surrounding thermoplastic softens and flows around the knurled exterior, creating a secure mechanical bond once cooled. A pilot hole diameter of 0.448 inches is required for proper seating. Minimum wall thickness of 0.13 inches must be maintained around the insert to ensure adequate retention strength.

Key Features

• 1/4-28 UNF internal thread for fine-pitch fastener engagement in plastic assemblies
• Brass construction resists corrosion and provides reliable thread durability over repeated use
• Headed design with 0.375 inch head diameter prevents pull-through in thin-wall applications
• Heat installation process bonds insert mechanically to thermoplastic without adhesives
• Overall length of 0.553 inches suits moderate wall thickness plastic components
• Sold in packages of 50, with no minimum order quantity requirement beyond a single package

Compatibility

Designed for heat installation into thermoplastic materials requiring a 0.448 inch pilot diameter and a minimum wall thickness of 0.13 inches around the insert bore. Suitable for any application accepting a 1/4-28 UNF fastener.

Installation Notes

Installation is performed by a technician or assembler using a temperature-controlled soldering iron or heat-set press fitted with the appropriate tip diameter. The host plastic must be a melt-compatible thermoplastic; thermoset plastics and composites are not suitable for heat installation. Confirm pilot hole diameter matches the required 0.448 inch specification before installation. Allow the insert to fully cool and the plastic to resolidify before applying any fastener torque.