S-91253A106 4-40 x 1/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 130,000 PSI ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Black-oxide finish on alloy steel provides enhanced corrosion resistance, extending the screw's service life in harsh industrial environments.
• Class 3A thread fit guarantees precise, tight-tolerance threading for secure, vibration-resistant connections in critical assemblies.
• Fully threaded design allows for maximum grip and uniform load distribution along the entire length, improving joint integrity.
• 82° countersink angle and flat head profile enable flush mounting for a smooth, professional finish and reduced snagging risks.
• Hex drive (1/16") facilitates easy installation and removal with standard tools, minimizing assembly time and labor costs.
• Compliance with ASME B18.3 and ASTM F835 standards ensures consistent quality, dimensional accuracy, and interoperability with other components.

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered to address common industrial challenges such as vibration loosening and corrosion in machinery, electronics, and automotive assemblies. The black-oxide alloy steel construction, combined with a Class 3A thread fit, delivers superior resistance to environmental wear and precise fastening in tight spaces. The coarse UNC threading and fully threaded body ensure quick installation and robust holding power, making them ideal for high-vibration applications where reliability is critical. Their 82° countersink design allows for seamless integration into surfaces, reducing protrusion and enhancing safety in moving parts. By meeting rigorous standards, these screws provide long-term value in industrial fastening systems, minimizing maintenance and downtime.

Specification Summary & Compliance

This screw features a 4-40 UNC coarse thread with Class 3A precision for tight tolerances, ensuring consistent performance. It adheres to ASME B18.3 and ASTM F835 manufacturing specifications, guaranteeing dimensional accuracy and reliability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting environmentally responsible and safe usage in global markets.