S-91259A624 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 84,000 psi minimum shear strength, ideal for heavy-duty industrial applications.
• Precise Class 3A thread fit ensures tight, reliable fastening with minimal play, reducing vibration loosening in machinery.
• Corrosion-resistant black oxide finish enhances longevity by protecting against rust and wear in harsh environments.
• High hardness of Rockwell C32 provides excellent resistance to deformation and wear over extended use.
• Knurled socket head with hex drive offers secure, non-slip tool engagement for easy installation and removal.
• Accurate shoulder dimensions with tight tolerances for consistent alignment and load distribution in assemblies.
• Compliance with major standards including ASME B18.3 and ASTM A574, ensuring reliability and safety in regulated industries.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision machinery and industrial equipment, where misalignment and component failure can lead to costly downtime. The 5/16"-18 UNC coarse threads with Class 3A fit provide superior holding power in high-vibration environments, such as automotive assemblies, robotics, and conveyor systems. The black oxide finish not only resists corrosion but also reduces friction during installation, while the knurled socket head ensures tool grip integrity under torque. With a robust shoulder diameter and length held to tight tolerances, it maintains exact positioning for bearings, pulleys, or gears, minimizing wear and extending service life in demanding applications like manufacturing and aerospace.

Specification Summary & Compliance

This shoulder screw features precise dimensions, including a shoulder diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005", ensuring consistent performance. It adheres to ASME B18.3 and ASTM A574 standards for manufacturing quality, with threads conforming to UNC coarse and Class 3A fit for high precision. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and suitability for global industrial use.