S-91259A636 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, this screw withstands extreme mechanical stresses in heavy-duty assemblies.
• Precision Shoulder Alignment – The 3" shoulder with tight length tolerance (±0.005") ensures accurate component positioning and reduces wear in rotating applications.
• Superior Corrosion Resistance – Black oxide finish provides durable protection against rust and oxidation, extending service life in harsh industrial environments.
• High-Strength Alloy Steel Construction – Made from alloy steel with Rockwell C32 hardness, offering excellent durability and fatigue resistance for long-term reliability.
• Secure Hex Drive Engagement – 3/16" hex drive and knurled head design prevent cam-out and allow for high-torque installation with standard tools.
• Class 3A Thread Precision – 5/16"-18 UNC coarse threads ensure reliable fastening and easy assembly in high-vibration applications.
• Full Regulatory Compliance – Meets ASME B18.3, ASTM A574, RoHS 3, and REACH standards, guaranteeing safety and environmental responsibility.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to solve critical alignment and load distribution challenges in precision machinery. The 3" shoulder length with controlled diameter tolerance acts as a precise pivot or axle, eliminating bushing wear in rotating assemblies, conveyor systems, and robotic arms. The black oxide finish enhances corrosion resistance where lubricants are present, while the coarse UNC threads provide rapid installation and vibration resistance in heavy equipment. With 140,000 psi tensile strength, it maintains joint integrity under dynamic loads, making it ideal for automation fixtures, press tools, and aerospace components where failure is not an option.

Specification Summary & Compliance

This shoulder screw features Class 3A thread fit for precise engagement, with shoulder diameter tolerance of -0.004" to -0.002" and length tolerance of ±0.005". Manufactured to ASME B18.3 specifications using ASTM A574 alloy steel, it complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring both mechanical excellence and regulatory adherence for global industrial use.