S-91259A483 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability with 140,000 psi tensile strength and Rockwell C32 hardness for reliable performance in demanding applications.
• Superior corrosion resistance provided by the black oxide finish, extending service life in harsh industrial environments.
• Precise shoulder fit and alignment with controlled shoulder diameter and length tolerances for accurate component positioning.
• Secure and slip-resistant installation thanks to the knurled socket head and 3/16" hex drive for firm tool grip.
• Wide compatibility and easy assembly with 5/16"-18 UNC coarse thread (Class 3A fit) ensuring quick engagement and reduced cross-threading risk.
• Compliance with major industry standards including ASME B18.3, RoHS 3, and REACH for assured quality and environmental safety.
• Versatile for precision applications featuring a 1-3/8" shoulder length and standard socket head profile for various mechanical assemblies.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical alignment and load-bearing challenges in precision machinery. The black oxide finish enhances corrosion resistance, making it suitable for environments exposed to moisture or chemicals. Its 5/16"-18 UNC coarse thread and Class 3A fit provide secure fastening with minimal installation effort, reducing assembly time and improving productivity. The knurled socket head and hex drive prevent tool slippage during torque application, ensuring consistent clamping force. Ideal for applications like rotating shafts, pivots, and guides, this screw offers reliable performance in industrial equipment, automotive systems, and automation technology, where exact shoulder diameter and length tolerances are crucial for minimizing play and vibration.

Specification Summary & Compliance

This shoulder screw adheres to ASME B18.3 specifications, with precise dimensions including a shoulder diameter of 3/8" (tolerance: -0.004" to -0.002") and shoulder length of 1-3/8" (tolerance: -0.005" to 0.005"). The UNC coarse thread follows Class 3A fit standards for high precision. It is manufactured from alloy steel under ASTM A574 and complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material integrity.