S-91259A635 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance in high-stress applications.
• Superior corrosion resistance thanks to the black oxide finish, extending service life in demanding industrial environments.
• Precision thread engagement with Class 3A thread fit ensuring secure fastening and vibration resistance in machinery assemblies.
• Enhanced grip and torque application from the knurled socket head and hex drive, allowing for easy installation and removal with standard tools.
• Accurate component alignment due to the 2-3/4" shoulder length with tight tolerances, minimizing misalignment in pivoting or rotating mechanisms.
• High durability and wear resistance from Rockwell C32 hardened alloy steel, reducing maintenance needs and downtime.
• Compliance with global standards including ASME B18.3, RoHS 3, and REACH, ensuring safety and environmental responsibility in procurement.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address common industrial challenges such as component misalignment, vibration-induced loosening, and corrosion in harsh environments. The black oxide finish provides a protective layer that resists rust, making it ideal for applications in automotive, aerospace, and heavy machinery where exposure to moisture or chemicals is frequent. The UNC coarse thread and Class 3A thread fit ensure quick assembly and reliable holding power, reducing the risk of thread stripping under dynamic loads. With a knurled socket head and hex drive, it offers superior torque transmission, facilitating efficient maintenance in tight spaces. The precise shoulder length and diameter tolerances enable exact positioning in linkages, bearings, and pivots, enhancing overall system accuracy and longevity while meeting rigorous ASME B18.3 specifications for consistent quality.

Specification Summary & Compliance

This shoulder screw features a 5/16"-18 UNC thread with Class 3A fit for high precision, and a shoulder diameter tolerance of -0.004" to -0.002" with length tolerance of -0.005" to 0.005" to ensure exact dimensional control. It is manufactured in compliance with ASME B18.3 standards and adheres to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and suitable for global industrial use.