S-91259A619 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance in high-stress applications.
• Superior corrosion resistance thanks to the black oxide finish, extending service life in harsh industrial environments.
• Precise thread engagement with Class 3A fit and UNC coarse thread spacing for secure, vibration-resistant fastening.
• Easy installation and removal using a standard 3/16" hex drive and knurled socket head for improved grip and torque application.
• Accurate shoulder dimensions with tight tolerances (shoulder diameter: -0.004" to -0.002", shoulder length: -0.005" to 0.005") for consistent alignment in assemblies.
• High hardness rating of Rockwell C32 ensures wear resistance and maintains structural integrity under repeated use.
• Compliance with industry standards including ASME B18.3, RoHS 3, and REACH for assured quality and environmental safety.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision machinery, automation systems, and heavy-duty equipment. The black oxide finish provides a protective layer against rust and oxidation, making it ideal for environments exposed to moisture or chemicals. Its 5/16"-18 UNC thread with coarse spacing and Class 3A fit ensures quick assembly and reliable hold, reducing the risk of loosening under vibration. The knurled socket head and hex drive allow for efficient torque application in confined spaces, while the precisely machined shoulder maintains component alignment, minimizing wear and extending the life of moving parts. Suitable for applications in robotics, conveyor systems, and industrial fixtures, this screw delivers consistent performance where high tensile and shear strength are paramount.

Specification Summary & Compliance

This shoulder screw adheres to ASME B18.3 specifications, with a Class 3A thread fit for precise dimensional accuracy. The thread follows UNC coarse spacing standards, and the shoulder diameter and length are manufactured within tight tolerance ranges for reliable performance. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it meets environmental and safety requirements for industrial use.