S-91264A539 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Secure vibration-resistant locking with permanent nylon pellet thread locker, maintaining integrity from -50° to 250°F for reliable performance in thermal cycling environments.
• Exceptional tensile and shear strength from alloy steel construction, rated at 140,000 psi tensile and 84,000 psi shear to prevent failure under high-stress loads.
• Precise Class 3A thread fit ensures smooth assembly and reduced risk of cross-threading, enhancing installation efficiency and joint reliability.
• Durable black oxide finish provides corrosion resistance and reduced galling, extending service life in industrial applications.
• Knurled hex socket head offers superior grip for easy installation and removal with standard tools, minimizing slippage and damage.
• Accurate shoulder dimensions with tight tolerances (e.g., shoulder diameter tolerance of -0.004" to -0.002") for precise alignment in pivoting or mounting assemblies.
• Compliance with ASME B18.3 and environmental standards including RoHS 3 and REACH, ensuring quality and regulatory adherence for global supply chains.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in industrial assembly, where components require exact alignment and resistance to dynamic forces. The 1/4"-20 UNC coarse threads with Class 3A fit facilitate quick, secure fastening in machinery, reducing downtime during maintenance. The integrated nylon pellet locking mechanism prevents loosening from vibrations in equipment like pivot joints or mounting systems, while the black oxide finish enhances durability against wear and mild corrosion. With a Rockwell C32 hardness and robust shoulder design, it serves as a reliable shaft or spacer in automotive, aerospace, and manufacturing setups, ensuring long-term performance without frequent replacements.

Specification Summary & Compliance

This shoulder screw adheres to ASME B18.3 specifications with Class 3A thread fit for precise UNC threading, and features a shoulder diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005" for consistent dimensional accuracy. It complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free of restricted substances, and meets material standards per ASTM A574 for high-strength alloy steel components.