S-91255A106 4-40 x 1/4" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability with 120,000 psi tensile strength and Rockwell C39 hardness for reliable performance in demanding applications
• Superior corrosion resistance provided by the black-oxide finish on alloy steel, extending service life in industrial environments
• Precise thread engagement with Class 3A thread fit ensuring secure fastening and vibration resistance
• Easy installation and removal with hex drive design requiring only 1/16" drive size for efficient assembly operations
• Optimized load distribution through the rounded button head design that minimizes surface stress and provides a finished appearance
• Maximum thread engagement with fully threaded design offering consistent holding power across the entire fastener length
• Industry standard compatibility with UNC coarse thread spacing and 4-40 thread size for broad application across equipment and machinery

Professional Applications & Engineering Value

These 4-40 UNC thread screws with Class 3A thread fit deliver critical engineering solutions for industrial applications where vibration resistance and reliable fastening are paramount. The black-oxide alloy steel construction provides superior corrosion protection while maintaining the high tensile strength required for structural applications. The combination of rounded head design and hex drive ensures easy installation in confined spaces while distributing clamp load effectively. These fully threaded button head screws are engineered to prevent loosening under dynamic loads, making them ideal for machinery, electronic enclosures, and precision equipment where coarse thread spacing facilitates quick assembly without compromising holding power.

Specification Summary & Compliance

Manufactured to exacting standards with Class 3A thread fit precision and UNC thread form specifications. These screws comply with ASME B18.3 and ASTM F835 manufacturing standards, ensuring dimensional accuracy and performance reliability. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) requirements, making them suitable for global industrial applications. The 1/4" length with fully threaded design maintains consistent mechanical properties throughout the fastener for uniform performance.