S-91259A437 1/2"-13 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Enhanced Durability – Alloy steel construction with Rockwell C32 hardness ensures long-term reliability in demanding industrial environments.
• Superior Corrosion Resistance – Black oxide finish provides excellent protection against rust, extending service life in harsh conditions.
• Precision Fit & Alignment – Class 3A thread fit and controlled shoulder diameter tolerances guarantee accurate, secure mounting with minimal play.
• High Load Capacity – 140,000 psi tensile strength and 84,000 psi shear strength support heavy-duty applications without failure.
• Easy Installation & Grip – Hex drive (5/16") and knurled head design allow for straightforward torque application and secure handling.
• Broad Compatibility – 1/2"-13 UNC coarse threads and standard shoulder fit ensure seamless integration with existing components and machinery.
• Regulatory Assurance – Complies with ASME B18.3, RoHS 3, and REACH standards, ensuring safety and environmental compliance.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision assembly and mounting systems. The Class 3A thread fit and precise shoulder dimensions minimize backlash and misalignment, which is vital in automated machinery, robotics, and fixture designs where repeatability is key. The black oxide finish enhances corrosion resistance, making it suitable for environments exposed to moisture or chemicals without compromising the 140,000 psi tensile strength. With a knurled head and hex drive, installation is efficient even in confined spaces, reducing assembly time. Ideal for pivots, axles, and guides, this screw ensures stable performance in high-stress applications, from automotive jigs to conveyor systems, by maintaining structural integrity under dynamic loads.

Specification Summary & Compliance

The screw features a 1/2"-13 UNC coarse thread with Class 3A fit for tight tolerances, a shoulder diameter of 5/8" (tolerance: -0.004" to -0.002"), and a shoulder length of 5/16" (tolerance: -0.005" to 0.005"). Manufactured to ASME B18.3 specifications using ASTM A574 alloy steel, it meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance for environmental safety.