S-91259A718 3/8"-16 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability with alloy steel construction and Rockwell C32 hardness, ensuring reliable performance in demanding applications.
• Superior corrosion resistance from the black oxide finish, extending service life in harsh industrial environments.
• Precise alignment and smooth rotation due to the knurled socket head and standard shoulder fit, reducing wear on mating components.
• High load-bearing capacity with 140,000 psi tensile strength and 84,000 psi minimum shear strength for heavy-duty use.
• Easy installation and removal using a standard 1/4" hex drive, saving time and labor in assembly processes.
• Accurate and secure fastening with Class 3A thread fit and UNC coarse threads, minimizing the risk of loosening under vibration.
• Compliance with industry standards including ASME B18.3, RoHS 3, and REACH, ensuring safety and regulatory adherence.

Professional Applications & Engineering Value

This 3/8"-16 UNC shoulder screw is engineered to address critical challenges in industrial machinery, automation, and precision equipment. The alloy steel material, combined with a black oxide finish, provides excellent resistance to corrosion and wear, making it ideal for environments exposed to moisture, chemicals, or high stress. The 1-3/4" shoulder length with tight tolerances ensures precise positioning of moving parts, such as gears or pulleys, reducing misalignment and extending component life. Its coarse threads and Class 3A fit offer reliable fastening in applications subject to vibration, while the knurled socket head allows for secure tool engagement during installation. Commonly used in robotics, conveyor systems, and automotive assemblies, this screw delivers consistent performance, minimizing downtime and maintenance costs.

Specification Summary & Compliance

This shoulder screw features a 3/8"-16 UNC thread with Class 3A fit for high precision, and a shoulder diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005" to ensure accurate assembly. It is manufactured in compliance with ASME B18.3 specifications and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards, confirming its suitability for global industrial use without hazardous substances.