S-91259A630 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capability: With a tensile strength of 140,000 psi and minimum shear strength of 84,000 psi, this shoulder screw ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior Corrosion Resistance: The black oxide finish provides enhanced protection against rust and wear, extending the screw's service life in harsh industrial environments.
• Precision Thread Fit for Secure Assembly: Class 3A thread fit with UNC coarse threads offers excellent engagement and vibration resistance, minimizing loosening in dynamic operations.
• High Durability and Wear Resistance: Made from alloy steel with Rockwell C32 hardness, it maintains structural integrity under repeated loads and abrasive conditions.
• Easy Installation and Adjustment: The knurled socket head with hex drive allows for quick, tool-friendly installation and secure gripping, speeding up assembly processes.
• Accurate Shoulder Dimensions for Alignment: Precise shoulder diameter and length tolerances ensure proper component alignment and spacing, reducing assembly errors and improving machine efficiency.
• Compliance with Industry Standards: Meets ASME B18.3, RoHS 3, and REACH regulations, guaranteeing safety, environmental responsibility, and interoperability in global supply chains.

Professional Applications & Engineering Value

This shoulder screw is engineered to address critical challenges in industrial settings, such as misalignment and vibration-induced failures. The alloy steel construction, combined with a black oxide finish, provides robust corrosion resistance and durability, making it ideal for machinery, automotive, and aerospace applications where exposure to moisture and high loads is common. The UNC coarse thread spacing and Class 3A thread fit ensure tight, reliable fastening that withstands dynamic stresses, while the knurled head and hex drive facilitate easy installation in confined spaces. By offering precise shoulder dimensions, it enables accurate pivoting and alignment in assemblies, reducing wear on components and minimizing maintenance downtime. This screw delivers consistent performance in demanding environments, supporting efficient production and long-term reliability.

Specification Summary & Compliance

The screw features a 5/16"-18 UNC thread with Class 3A fit for high precision, along with shoulder diameter and length tolerances (e.g., -0.004" to -0.002" for diameter) to ensure exacting standards. It complies with ASME B18.3 manufacturing specifications, ASTM A574 material standards, and environmental regulations including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), affirming its suitability for rigorous industrial and international use.