S-91259A621 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capacity: With a tensile strength of 140,000 psi and minimum shear strength of 84,000 psi, this shoulder screw provides reliable performance in high-stress applications, reducing the risk of mechanical failure.
• Superior Wear and Corrosion Resistance: The alloy steel construction with black oxide finish offers enhanced durability and protection against rust, extending service life in harsh industrial environments.
• Precision Thread Fit for Secure Fastening: Class 3A thread fit ensures tight, vibration-resistant connections, minimizing loosening and improving assembly reliability in dynamic operations.
• Easy Installation and Adjustment: The knurled socket head with hex drive allows for quick, tool-friendly installation and removal, saving time and labor in maintenance and assembly tasks.
• Accurate Shoulder Alignment: Tight tolerances on shoulder diameter and length (-0.004" to -0.002" and -0.005" to 0.005", respectively) ensure precise component positioning, reducing misalignment issues in machinery.
• High Hardness for Long-Term Use: Rockwell C32 hardness provides excellent resistance to deformation and wear, maintaining integrity over repeated cycles in demanding applications.
• Compliance with Industry Standards: Meets ASME B18.3 specifications and environmental regulations like RoHS 3 and REACH, ensuring safety and reliability for global industrial use.

Professional Applications & Engineering Value

This shoulder screw is engineered to address common challenges in precision machinery, such as component misalignment and vibration-induced loosening. The alloy steel material, combined with a black oxide finish, enhances corrosion resistance, making it ideal for environments exposed to moisture or chemicals. The UNC coarse threads and Class 3A fit provide a secure, tight hold that withstands dynamic loads, reducing maintenance needs in applications like automotive assemblies, industrial robots, and conveyor systems. The 3/8" shoulder diameter with precise tolerances ensures accurate alignment of parts, preventing wear and improving operational efficiency. By integrating high tensile and shear strength, this screw supports heavy-duty use while the knurled socket head allows for easy installation with standard hex tools, streamlining assembly processes in B2B settings.

Specification Summary & Compliance

This shoulder screw features a 5/16"-18 UNC thread with Class 3A fit for high precision, and shoulder dimensions including a diameter of 3/8" (tolerance: -0.004" to -0.002") and length of 5/8" (tolerance: -0.005" to 0.005"). It complies with ASME B18.3 manufacturing standards, ensuring consistent quality, and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations for environmental safety and substance control.