S-91259A505 2-56 ASTM A108 Shoulder Screws

Key Features & Benefits at a Glance

• Enhanced Durability: Alloy steel construction with Rockwell C32 hardness provides superior wear resistance and longevity in demanding industrial environments.
• High Tensile Strength: 140,000 psi tensile strength ensures reliable performance under heavy loads and vibration, reducing failure risks.
• Corrosion Resistance: Black oxide finish offers effective protection against rust and oxidation, extending service life in harsh conditions.
• Precision Thread Fit: Class 3A UNC coarse threads deliver secure, accurate fastening with minimal backlash for consistent assembly quality.
• Secure Grip & Easy Installation: Knurled socket head with 5/64" hex drive allows for firm tool engagement and straightforward torque application.
• Accurate Shoulder Alignment: Tight shoulder diameter and length tolerances ensure precise component positioning and reduced assembly errors.
• Broad Compliance: Meets ASTM A108, RoHS 3, and REACH standards, guaranteeing material consistency and environmental safety for global supply chains.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision machinery, automation systems, and rotating assemblies. The 2-56 UNC coarse thread with Class 3A fit ensures rapid, secure fastening while minimizing cross-threading risks in high-cycle applications. The black oxide finish enhances corrosion resistance, making it suitable for environments exposed to moisture or chemicals. With a 1/2" shoulder length and controlled tolerances, it provides exact axial positioning for bearings, pulleys, or linkages, reducing wear and maintaining alignment. The knurled socket head and hex drive facilitate easy installation in confined spaces, supporting efficient maintenance and reducing downtime in industrial operations.

Specification Summary & Compliance

This shoulder screw adheres to UNC thread standards with Class 3A precision fit for consistent engagement. Dimensions include a thread diameter of 0.086", shoulder diameter of 3/32" (tolerance: -0.004" to -0.002"), and shoulder length of 1/2" (tolerance: -0.005" to 0.005"). It conforms to ASTM A108 for material properties, and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental and safety standards are met for industrial use.