S-94383A240 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Strength & Durability: Withstands high-stress applications thanks to 140,000 psi tensile strength and 84,000 psi shear strength, ensuring reliable performance in demanding environments.
• Superior Corrosion Resistance: Black oxide finish provides enhanced protection against rust and corrosion, extending the screw's service life in harsh industrial conditions.
• Precision Thread Fit: Class 3A thread fit ensures tight, secure fastening with minimal backlash, improving assembly accuracy and vibration resistance.
• Secure & Easy Installation: Hex socket drive (5/32") combined with a knurled head allows for firm tool grip and efficient torque application, reducing installation time and slippage.
• Accurate Shoulder Positioning: Tight tolerances on shoulder diameter (-0.004" to -0.002") and length (-0.005" to 0.005") enable precise component alignment and rotational control.
• High Material Hardness: Rockwell C32 hardness offers excellent wear resistance, maintaining dimensional stability under repeated use and load.
• Broad Regulatory Compliance: Meets ASME B18.3, RoHS 3, and REACH standards, ensuring safety, environmental responsibility, and global acceptability for industrial projects.

Professional Applications & Engineering Value

This alloy steel shoulder screw with 1/4-20 UNC coarse threads and black oxide finish is engineered to address critical challenges in precision machinery, automation systems, and rotating assemblies. The knurled head and hex socket drive facilitate secure handling and high-torque installation, minimizing the risk of cam-out in confined spaces. Its Class 3A thread fit ensures consistent clamping force, reducing loosening from vibrations in dynamic applications like motor mounts or conveyor systems. The precisely machined shoulder (5/16" diameter, 5/8" length) serves as an accurate pivot or spacer, maintaining alignment in bushings, bearings, and linkages. By combining high tensile and shear strength with corrosion resistance, this screw enhances assembly longevity and reliability in industrial settings, from manufacturing equipment to automotive components.

Specification Summary & Compliance

This shoulder screw adheres to strict dimensional standards, including Class 3A thread fit for precision and UNC coarse threads (1/4"-20) for robust engagement. Manufacturing follows ASME B18.3 specifications, with material certification per ASTM A574. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) confirms environmental safety, free from restricted substances. Shoulder diameter and length tolerances are tightly controlled to ensure consistent performance in high-precision applications.