S-91864A043 6-40 x 5/16" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Superior thread precision with Class 3A fit provides tighter tolerances and improved thread engagement, minimizing backlash and enhancing assembly integrity.
• Corrosion-resistant black-oxide coating on alloy steel offers increased durability and protection against rust in harsh industrial environments.
• Fine UNF thread design delivers better vibration resistance and more precise adjustments compared to coarse threads, ideal for precision machinery.
• Fully threaded shank allows for consistent clamping force along the entire length, ensuring secure fastening in varied material thicknesses.
• Hex socket drive with 7/64" size enables high-torque installation and removal, reducing tool slippage and improving workshop efficiency.
• Hardened to Rockwell C37 for excellent wear resistance, extending the screw's service life in high-cycle applications.

Professional Applications & Engineering Value

This 6-40 UNF socket head cap screw is engineered to address critical challenges in precision assembly and heavy-duty machinery. The black-oxide alloy steel construction combats corrosion while maintaining high tensile strength, making it suitable for automotive, aerospace, and industrial equipment where reliability is paramount. The fine UNF threads and Class 3A fit ensure secure fastening in vibration-prone environments, reducing maintenance needs. Its fully threaded design provides uniform load distribution, ideal for applications requiring consistent clamping force across components of varying thicknesses. By integrating high hardness (Rockwell C37) and compliance with industry standards, this fastener delivers long-term performance in CNC systems, robotics, and precision tooling.

Specification Summary & Compliance

This socket head cap screw features precise Class 3A thread fit per UNF standards, with a right-hand thread direction and fine thread spacing. Dimensions include a 5/16" length, 0.226" head diameter, and 7/64" hex drive size. It is manufactured in accordance with ASTM A574 specifications and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safety and sustainability in industrial use.