S-91259A434 5/16"-18 ASME B18.3, ASTM A108 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Durability – Crafted from high-strength alloy steel with a Rockwell C32 hardness, ensuring long-lasting performance in demanding industrial environments.
• Precision Alignment – Features a Class 3A thread fit and controlled shoulder diameter tolerance (-0.004" to -0.002") for accurate assembly and reduced wear.
• Corrosion Resistance – Black oxide finish provides reliable protection against rust, extending service life in various operating conditions.
• Secure Fastening – UNC coarse threads and knurled head design offer superior grip and ease of installation with a 3/16" hex drive.
• High Load Capacity – With a tensile strength of 140,000 psi, this shoulder screw handles heavy loads and stress without failure.
• Industry Compliance – Meets ASME B18.3 standards and is RoHS 3 and REACH compliant, ensuring safety and regulatory adherence.
• Versatile Shoulder Design – The 4 3/4" shoulder length with standard fit allows for precise component spacing and rotational movement in machinery.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision machinery, such as misalignment and component wear. The 5/16"-18 UNC coarse threads with Class 3A fit ensure tight tolerances, reducing vibration and improving assembly accuracy in automated systems. The black oxide finish enhances corrosion resistance, making it ideal for environments exposed to moisture or chemicals. Commonly used in robotics, conveyor systems, and manufacturing equipment, the 4 3/4" shoulder length provides a reliable pivot or bearing surface, minimizing friction and extending the lifespan of moving parts. Its high tensile strength and knurled head further support secure fastening in high-stress applications, delivering consistent performance and reducing maintenance downtime.

Specification Summary & Compliance

This shoulder screw adheres to Class 3A thread fit per UNC standards, with precise shoulder diameter tolerance of -0.004" to -0.002" and shoulder length tolerance of -0.005" to 0.005". It conforms to ASME B18.3 manufacturing specifications and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and industrial reliability.