S-91263A962 4-40 x 3/4" ASME B18.3 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 120,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance from zinc plating protects against rust and extends service life in harsh industrial environments.
• Precise Class 3A thread fit guarantees tight, secure fastening with minimal play, enhancing assembly accuracy and vibration resistance.
• Fully threaded design provides maximum grip and holding power along the entire length, ideal for materials requiring deep engagement.
• Standard 82° countersink angle allows for a flush, low-profile finish, improving aesthetics and preventing snagging in assembled products.
• Hex drive compatibility enables easy installation and removal with common tools, speeding up assembly and maintenance processes.
• Compliance with major standards including ASME B18.3 ensures consistent quality and interchangeability in regulated industries.

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered from zinc-plated alloy steel to address common industrial challenges such as corrosion, vibration loosening, and high mechanical stress. The coarse thread spacing and Class 3A thread fit provide excellent grip in soft materials and metals, reducing the need for frequent retightening in machinery, electronics, and automotive assemblies. The fully threaded design ensures uniform load distribution, while the 82° countersink angle offers a seamless finish in countersunk holes, preventing protrusion and improving safety. Ideal for heavy-duty industrial fasteners applications, these screws deliver reliable performance in environments where durability and regulatory compliance are critical.

Specification Summary & Compliance

This product adheres to Class 3A thread fit tolerances as per UNC standards, ensuring precise dimensional accuracy. Manufacturing follows ASME B18.3 specifications, with full compliance to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of hazardous substances. The screws are fully threaded with a right-hand thread direction and coarse spacing, meeting rigorous industry requirements for reliability and safety.