S-91253A314 1/4"-28 x 1 3/8" 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 in high-stress industrial applications, reducing the risk of fastener failure.
• Precision Class 3A thread fit provides tighter tolerances for secure, vibration-resistant connections in critical assemblies.
• Black-oxide coating on alloy steel offers superior corrosion resistance, extending service life in demanding environments.
• Fully threaded design allows for maximum grip and load distribution along the entire length, enhancing joint integrity.
• 82° countersink angle with standard flat head enables flush mounting for a smooth, professional finish and reduced snagging.
• Hex drive compatibility (5/32") facilitates easy installation and removal with standard tools, speeding up assembly processes.
• Fine UNF threading (1/4"-28) delivers improved holding power in materials where coarse threads may not be suitable.

Professional Applications & Engineering Value

Engineered for demanding industrial settings, these black-oxide alloy steel flat head screws address common challenges like vibration loosening and corrosion. The Class 3A UNF fine threads provide superior engagement in precision machinery, automotive components, and electronic enclosures, minimizing the need for frequent retightening. With a Rockwell C39 hardness and full threading, they ensure consistent clamping force in high-vibration environments, reducing maintenance downtime. The 82° countersink angle allows for seamless integration into tapered holes, ideal for aerospace and manufacturing applications where aerodynamics and surface smoothness are critical. This combination of high tensile strength and compliant standards makes them a reliable choice for engineers seeking durability and regulatory adherence.

Specification Summary & Compliance

This screw meets ASTM F835 specifications for mechanical properties and dimensional accuracy, with a Class 3A thread fit ensuring precise tolerances per UNF standards. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of hazardous substances. The right-hand, fine threading and inch system measurements adhere to industrial norms for interoperability and quality assurance.