S-90390A125 5/16"-18 x 3 1/2" Tapping Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-phosphate steel construction, extending service life in demanding environments
• Maximum torque transmission and reduced cam-out with T40 Torx drive, ensuring secure installation and preventing tool slippage
• Efficient thread cutting action (Type F) creates precise mating threads in tough materials like aluminum, brass, and cast iron
• Reliable fastening in sheet metal and other materials with UNC coarse threading and a blunt tip for controlled starting
• Clean, flush installation with a standard flat head and 82° countersink angle for a professional finish
• Full 3 1/2" length and complete threading provides consistent grip and holding power throughout the entire fastener
• Simplified installation process with clear guidance for a pre-drilled L-size (0.29") hole for optimal performance

Professional Applications & Engineering Value

This high-performance thread cutting screw is engineered to solve common fastening challenges in metal fabrication and assembly. The black-phosphate steel provides a durable, corrosion-resistant base, essential for components exposed to harsh conditions. Its Type F thread cutting design and UNC coarse thread form allow it to tap its own mating threads in aluminum, brass, cast iron, and sheet metal, eliminating the need for pre-tapped holes and speeding up production. The T40 Torx drive is critical for high-torque applications, preventing stripping and ensuring the screw is seated correctly with a flush flat head profile. This combination of features delivers reliable, vibration-resistant connections that reduce assembly time and improve the longevity of the final product.

Specification Summary & Compliance

This screw conforms to standard dimensional and thread specifications, including a 5/16"-18 UNC coarse thread and a standard 82° countersink angle for the flat head. It is a fully threaded, right-hand thread cutting screw (Tapping Screw Type F) designed for use with a pre-drilled hole of 0.29" diameter (Drill Bit Size L). The manufacturing and material quality ensure consistent performance for industrial applications.