S-91264A591 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Tensile and Shear Strength: With 140,000 psi tensile and 84,000 psi shear strength, this shoulder screw provides reliable performance in high-stress applications, reducing the risk of fastener failure.
• Precision Alignment and Stability: The 2" shoulder length with tight tolerances (±0.005") ensures accurate component positioning and minimizes misalignment in assemblies.
• Secure Vibration-Resistant Locking: Integrated nylon pellet thread locker maintains tight fastening from -50° to 250°F, preventing loosening under dynamic loads and temperature fluctuations.
• Corrosion-Resistant and Durable Finish: Black oxide coating on alloy steel enhances corrosion resistance and wear, extending service life in harsh industrial environments.
• High-Precision Thread Fit: Class 3A thread fit offers superior accuracy and ease of assembly, reducing installation time and improving joint integrity.
• Easy Installation and Removal: Socket head with hex drive allows for simple tool engagement in confined spaces, streamlining maintenance and assembly processes.
• Compliance with Industry Standards: Meets ASME B18.3 specifications and RoHS 3/REACH regulations, ensuring quality and environmental safety for global supply chains.

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw is engineered to address common challenges in precision machinery and industrial equipment, such as misalignment and vibration-induced loosening. The alloy steel construction, combined with a Rockwell C32 hardness, delivers high durability under repetitive loads, while the black oxide finish provides added corrosion resistance for extended use in demanding conditions. The 2" shoulder length with minimal tolerances ensures exact alignment in applications like rotating shafts, bearings, and linkages, reducing wear and maintenance costs. Integrated nylon pellet thread locking secures fasteners in high-vibration environments, from automotive assemblies to manufacturing tools, enhancing operational reliability. By incorporating UNC coarse threads and a socket head design, it simplifies installation in tight spaces, making it ideal for OEM and MRO applications requiring consistent performance.

Specification Summary & Compliance

This shoulder screw adheres to precise dimensional standards, including a Class 3A thread fit for superior accuracy and a shoulder diameter tolerance of -0.004" to -0.002". It complies with ASME B18.3 manufacturing specifications and is certified RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, ensuring environmental safety and regulatory adherence for industrial use.