S-91255A101 3-56 x 3/8" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating for reliable performance in demanding industrial environments
• Precision thread engagement with Class 3A fit ensures secure fastening and vibration resistance in critical applications
• Superior mechanical strength with 120,000 psi tensile strength and Rockwell C39 hardness for heavy-duty fastening requirements
• Optimized fine thread design provides enhanced grip and load distribution compared to coarse thread alternatives
• Streamlined installation with hex drive design allowing for efficient torque application and space-constrained access
• Full thread coverage along the 3/8" length maximizes engagement surface for superior holding power
• Regulatory compliance assurance meeting ASME B18.3, ASTM F835, RoHS 3, and REACH standards for global industrial acceptance

Professional Applications & Engineering Value

These 3-56 UNF fine thread rounded button head screws deliver exceptional engineering value in precision assembly applications where space constraints and vibration resistance are critical concerns. The black-oxide alloy steel construction provides superior corrosion protection while maintaining the high tensile strength required for demanding mechanical assemblies. The fully threaded design with Class 3A precision ensures maximum thread engagement in thin materials and delicate components, preventing loosening under dynamic loads. The rounded button head profile combined with hex drive functionality offers both aesthetic appeal and practical installation advantages in electronics, aerospace components, and precision machinery where low-profile fastening solutions are essential for optimal performance and reliability.

Specification Summary & Compliance

Manufactured to exacting Class 3A thread fit tolerances with UNF fine thread specifications (3-56 thread size, 0.099" diameter). Compliant with ASME B18.3 dimensional standards and ASTM F835 mechanical properties. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance requirements. Features right-hand threading direction with standard rounded head profile and 1/16" hex drive for consistent installation performance across industrial applications.