S-91259A428 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance in high-stress applications.
• Superior corrosion resistance from the black oxide finish, extending service life in harsh industrial environments.
• Precision thread engagement with Class 3A fit and UNC coarse threads ensuring secure, vibration-resistant fastening.
• Enhanced durability from Rockwell C32 hardness and alloy steel construction, minimizing wear and deformation.
• Easy installation and removal with a 5/32" hex drive and knurled socket head for improved grip and torque application.
• Accurate component alignment thanks to the 7/16" shoulder length with tight tolerances for consistent positioning.
• Compliance with industry standards including ASME B18.3, RoHS 3, and REACH for safe, regulated use in global markets.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in industrial applications where precision alignment and high strength are paramount. The black oxide finish provides a protective layer against rust and corrosion, making it ideal for machinery exposed to moisture or chemicals. Its UNC coarse threads and Class 3A thread fit ensure quick assembly and reliable holding power, reducing the risk of loosening under vibration. The 7/16" shoulder length with minimal tolerances allows for exact component spacing in assemblies like pivots, gears, and linkages, enhancing overall system accuracy. With a Rockwell C32 hardness and robust alloy steel construction, it withstands repetitive loads and impacts, minimizing maintenance needs in heavy-duty equipment and automation systems.

Specification Summary & Compliance

This shoulder screw features precise dimensions, including a shoulder diameter tolerance of -0.004" to -0.002" and shoulder length tolerance of -0.005" to 0.005", ensuring consistent fit in precision assemblies. Threads adhere to UNC standards with a Class 3A fit for optimal engagement. Manufactured in compliance with ASME B18.3 specifications and meeting RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, it supports safe, environmentally responsible use across various sectors.