S-91259A582 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Enhanced Durability & Corrosion Resistance: Black oxide finish provides superior protection against rust and wear, extending service life in harsh industrial environments.
• Exceptional Mechanical Strength: Made from high-grade alloy steel with 140,000 psi tensile strength and 84,000 psi shear strength, ensuring reliable performance under heavy loads.
• Precision Thread Fit: Class 3A UNC coarse threads offer secure, vibration-resistant fastening with reduced risk of cross-threading during assembly.
• Secure Hex Drive Engagement: 5/32" hex socket drive allows for high-torque installation and removal, minimizing tool slippage and damage.
• Accurate Shoulder Alignment: Tight shoulder diameter and length tolerances ensure precise component positioning and smooth rotational movement.
• Knurled Head for Improved Grip: Easy manual handling and adjustment, even in oily or gloved conditions.
• Broad Regulatory Compliance: Meets ASME B18.3, RoHS 3, and REACH standards, guaranteeing safety and environmental responsibility.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical alignment and load-bearing challenges in precision assemblies. The 1/4-20 UNC coarse thread and Class 3A fit provide robust, reliable fastening that resists loosening under vibration, making it ideal for machinery, automotive, and aerospace applications. The black oxide finish enhances corrosion resistance, crucial for components exposed to moisture or chemicals. With a 7/8" shoulder length and tight diameter tolerances, it ensures accurate spacing and smooth rotation of parts like gears, pulleys, and linkages. The combination of high tensile and shear strength supports heavy-duty use, while the socket head design facilitates easy installation in confined spaces, reducing assembly time and improving maintenance efficiency.

Specification Summary & Compliance

This shoulder screw features a 1/4-20 UNC coarse thread with Class 3A fit for precise engagement, and shoulder dimensions with tolerances (diameter: -0.004" to -0.002", length: -0.005" to 0.005") to ensure accurate alignment. It is manufactured in compliance with ASME B18.3 specifications and ASTM A574 material standards, and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for safe industrial use.