S-91264A578 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capability with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance in high-stress applications.
• Secure, vibration-resistant fastening thanks to the integrated nylon pellet thread locker, maintaining integrity across a wide temperature range from -50° to 250°F.
• Precise alignment and smooth rotation ensured by the standard shoulder fit and knurled head, reducing wear and simplifying assembly.
• Superior corrosion resistance from the black oxide finish, extending service life in harsh industrial environments.
• High thread accuracy and durability with Class 3A thread fit and coarse UNC threading, providing consistent engagement and reducing cross-threading risks.
• Easy installation and removal using a standard 3/16" hex drive, compatible with common tools for efficient maintenance.
• Compliance with rigorous industry standards including ASME B18.3 and ASTM A574, ensuring quality and reliability for engineering applications.

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw is engineered to address critical challenges in machinery assembly, automation systems, and precision equipment. The alloy steel construction, combined with a black oxide finish, offers robust resistance to corrosion and wear, ideal for environments exposed to moisture or chemicals. The shoulder diameter and length provide exact positioning for rotating parts like bearings and pulleys, minimizing misalignment and reducing maintenance downtime. Integrated nylon pellet thread locker ensures joints remain secure under vibration, preventing loosening in dynamic applications such as conveyor systems or motor mounts. By meeting ASME B18.3 specifications, it delivers consistent performance in industrial shoulder screws, enhancing operational safety and efficiency.

Specification Summary & Compliance

This shoulder screw features precision Class 3A thread fit with UNC coarse threading for reliable engagement. Dimensions include a shoulder diameter of 3/8" (tolerance: -0.004" to -0.002") and shoulder length of 1/2" (tolerance: -0.005" to 0.005"), ensuring accurate assembly. It complies with ASME B18.3 and ASTM A574 standards, and is RoHS 3 and REACH compliant, supporting environmentally responsible manufacturing practices.