S-91259A493 4-40 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Durability: Crafted from high-grade alloy steel with a black oxide finish to provide superior corrosion resistance, extending service life in demanding industrial environments.
• High Tensile & Shear Strength: Delivers a robust 140,000 psi tensile strength and 84,000 psi minimum shear strength, ensuring reliable performance under heavy loads and preventing joint failure.
• Precision Thread Fit: Features a Class 3A thread fit for tighter tolerances and secure, vibration-resistant fastening in precision assemblies.
• Optimized Shoulder Design: The smooth, standard shoulder with precise diameter and length tolerances provides accurate alignment and acts as a pivot or bearing surface, reducing wear on components.
• Easy Installation & Removal: Equipped with a socket head and 5/64" hex drive, allowing for high-torque application with standard tools in confined spaces.
• Industry Compliance & Safety: Meets ASME B18.3 specifications and is RoHS 3 and REACH compliant, ensuring adherence to international standards for safety and environmental regulations.
• Consistent Hardness: Maintains Rockwell C32 hardness for excellent wear resistance and durability, ensuring long-term reliability in dynamic applications.

Professional Applications & Engineering Value

This 4-40 UNC thread shoulder screw is engineered to address critical challenges in precision machinery and industrial assemblies. The alloy steel construction, combined with the black oxide finish, offers enhanced resistance to corrosion and wear, making it ideal for environments exposed to moisture, chemicals, or frequent movement. The Class 3A thread fit and precise shoulder dimensions ensure accurate alignment and secure fastening, reducing the risk of misalignment and component slippage in applications such as rotating shafts, linkages, and bearing supports. Its high tensile and shear strength provides reliable performance in high-stress situations, while the socket head design allows for efficient installation in tight spaces, streamlining assembly processes and minimizing downtime. This screw is a trusted solution for engineers seeking durability, precision, and compliance in industrial shoulder fasteners.

Specification Summary & Compliance

This shoulder screw adheres to strict dimensional tolerances, including a Class 3A thread fit for superior accuracy and a shoulder diameter tolerance of -0.004" to -0.002". It conforms to the ASME B18.3 standard for consistency and reliability in manufacturing. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it meets environmental and safety requirements for global industrial use.