S-91255A559 1/4"-28 x 1" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 120,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Black-oxide coating on alloy steel provides enhanced corrosion resistance, extending the screw's service life in demanding environments.
• Class 3A thread fit offers superior precision and tighter tolerances for secure, vibration-resistant assemblies.
• Fully threaded design allows for maximum grip and uniform load distribution along the entire length.
• Hex drive (5/32") enables easy installation and high torque application with standard tools, minimizing assembly time.
• Rockwell C39 hardness ensures excellent wear resistance and durability under repeated use.
• Compliance with ASME B18.3 and ASTM F835 guarantees consistent quality and interoperability in industrial settings.

Professional Applications & Engineering Value

This 1/4"-28 UNF rounded head screw is engineered to address critical challenges in industrial assembly, such as vibration loosening and material fatigue. The black-oxide alloy steel construction provides a robust barrier against rust and oxidation, making it ideal for machinery, automotive, and outdoor equipment where environmental exposure is a concern. Its fine thread spacing and Class 3A fit ensure a tight, secure connection that maintains integrity under dynamic loads. The button head style with a hex drive offers a low-profile, flush finish while allowing for efficient installation in confined spaces. These features collectively enhance assembly reliability, reduce maintenance needs, and support long-term operational efficiency in high-strength fastener applications.

Specification Summary & Compliance

This screw features a 1/4"-28 UNF thread with Class 3A precision fit and fully threaded design for consistent engagement. It adheres to ASME B18.3 and ASTM F835 standards, ensuring dimensional accuracy and performance reliability. The product is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting environmental and safety regulations for industrial use.