S-91264A540 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking: Integrated nylon pellet thread locker maintains secure fastening in temperatures from -50° to 250° F, preventing loosening in dynamic applications.
• Exceptional strength and durability: Made from hardened alloy steel with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance under heavy loads.
• Precise alignment and smooth rotation: Features a 3/4" shoulder with controlled diameter tolerance for accurate component positioning and reduced wear.
• Corrosion-resistant protection: Black oxide finish provides a durable layer that resists rust and extends service life in harsh environments.
• High-accuracy threading: Class 3A thread fit on the 1/4"-20 UNC coarse thread ensures tight, reliable engagement and easy assembly.
• Secure and efficient installation: Socket head with 5/32" hex drive and knurled texture allows for high-torque application and improved grip.
• Regulatory compliance assurance: Meets ASME B18.3 specifications and is RoHS 3/REACH compliant for safe, industry-approved use.

Professional Applications & Engineering Value

This 1/4"-20 UNC shoulder screw is engineered to address critical challenges in industrial assembly and precision machinery. The alloy steel construction with Rockwell C32 hardness provides superior resistance to deformation and fatigue, making it ideal for high-stress applications like rotating shafts, pivots, and gear assemblies. The nylon pellet thread locker effectively counters vibration-induced loosening, ensuring long-term fastener integrity in equipment subject to constant motion. Combined with the black oxide finish, it offers enhanced corrosion protection, reducing maintenance needs in humid or chemically exposed settings. The precise shoulder diameter and length facilitate exact component alignment, minimizing misalignment issues and extending the lifespan of connected parts. This screw delivers reliable performance in automotive, aerospace, and heavy machinery sectors where high tensile strength and secure fastening are non-negotiable.

Specification Summary & Compliance

This shoulder screw features a Class 3A thread fit with UNC coarse threading for precise engagement, and adheres to ASME B18.3 manufacturing standards. The shoulder diameter tolerance is -0.004" to -0.002", and shoulder length tolerance is -0.005" to 0.005", ensuring dimensional accuracy. It is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and suitable for global industrial use.