S-91259A633 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 minimum shear strength for reliable performance in high-stress applications.
• Precision alignment and smooth rotation ensured by the 2-1/4" shoulder with tight ±0.005" length tolerance and standard shoulder fit.
• Superior corrosion resistance provided by the black oxide finish, extending service life in demanding industrial environments.
• High-durability construction from alloy steel with Rockwell C32 hardness, offering excellent wear resistance and long-term reliability.
• Secure and precise fastening with Class 3A thread fit and 5/16"-18 UNC coarse thread, reducing the risk of cross-threading and ensuring consistent engagement.
• Easy installation and removal facilitated by the hex socket drive and knurled head, allowing for better grip and torque application with standard tools.
• Compliance with major industry standards including ASME B18.3 and ASTM A574, guaranteeing consistent quality and interoperability in professional settings.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical alignment and durability challenges in precision machinery, automation systems, and heavy-duty equipment. The 2-1/4" shoulder length with minimal tolerance (±0.005") provides a stable bearing surface for rotating components like gears, pulleys, and linkages, minimizing wear and maintaining precise positioning. The black oxide finish enhances corrosion resistance, making it suitable for environments exposed to moisture or chemicals. With a Class 3A thread fit and UNC coarse thread, it ensures quick assembly and high clamping force, reducing installation time and preventing loosening under vibration. Ideal for use in manufacturing jigs, conveyor systems, and robotic arms, this screw delivers reliable performance where exact alignment and high tensile strength are paramount.

Specification Summary & Compliance

This shoulder screw adheres to Class 3A thread fit for precise engagement and meets ASME B18.3 and ASTM A574 specifications, ensuring dimensional accuracy and material integrity. The shoulder diameter tolerance is tightly controlled at -0.004" to -0.002", while the shoulder length tolerance is ±0.005". It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of hazardous substances and supporting environmental safety in industrial applications.