S-91263A255 1/4"-28 x 3/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength (130,000 PSI) ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Class 3A thread fit precision provides tighter tolerances for superior thread engagement and vibration resistance in critical assemblies.
• Zinc-plated alloy steel construction offers enhanced corrosion resistance, extending service life in harsh industrial environments.
• Fully threaded design maximizes grip and load distribution along the entire length for improved holding power.
• 82° countersink angle and flat head profile allow for flush mounting, minimizing protrusion and creating a smooth surface finish.
• Hex drive (5/32") compatibility enables easy installation with standard tools, reducing assembly time and labor costs.
• Fine UNF threading (1/4"-28) delivers precise adjustment and secure fastening in applications requiring fine pitch accuracy.

Professional Applications & Engineering Value

These zinc-plated alloy steel flat head screws are engineered to address common industrial challenges such as vibration loosening, corrosion degradation, and high-load requirements. The Class 3A UNF fine thread configuration ensures minimal backlash and superior clamp force retention in precision machinery, automotive components, and electronic enclosures. With a Rockwell C39 hardness and 130,000 PSI tensile strength, they provide dependable performance in heavy-duty applications where material integrity is critical. The 82° countersink design facilitates seamless integration into tapered seats, preventing head protrusion and enhancing aerodynamic or aesthetic profiles. Ideal for industrial assembly lines, these screws offer long-term reliability and compliance with stringent industry standards.

Specification Summary & Compliance

This product adheres to Class 3A thread fit tolerances per UNF standards, ensuring precise dimensional accuracy. Manufacturing specifications meet ASTM F835 for consistent quality and performance. The screws are fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and material restrictions adherence. Threading is fully executed with a right-hand direction and fine spacing (1/4"-28), optimized for secure fastening in high-vibration environments.