S-90298A578 1/4"-20 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 Stainless Steel construction and passivated finish, ensuring long-term reliability in harsh environments.
• High tensile strength of 70,000 psi provides dependable load-bearing capacity for demanding mechanical assemblies.
• Precision Class 3A thread fit guarantees secure, vibration-resistant fastening with minimal backlash in critical applications.
• Knurled socket head with 5/32" hex drive offers excellent grip and torque transmission, reducing tool slippage during installation.
• Tight shoulder tolerances (±0.001" diameter, ±0.005" length) enable exact positioning and alignment in precision machinery and fixtures.
• Rockwell B55 hardness ensures durability and wear resistance under repeated use and high-stress conditions.
• Compliance with ASME B18.3, RoHS 3, and REACH assures adherence to industry standards and environmental regulations for global supply chain compatibility.

Professional Applications & Engineering Value

This 1/4"-20 UNC thread shoulder screw is engineered to address critical alignment and mounting challenges in industrial equipment. The 18-8 Stainless Steel material, combined with a passivated finish, resists oxidation and chemical exposure, making it ideal for food processing, medical devices, and outdoor machinery. The Class 3A thread fit and precise shoulder dimensions prevent misalignment in rotating assemblies, such as bearings, pulleys, and gears, reducing wear and maintenance downtime. Its socket head design with knurling ensures easy installation in confined spaces, while the 70,000 psi tensile strength supports high-load applications in automation and aerospace sectors, delivering consistent performance and longevity.

Specification Summary & Compliance

This shoulder screw features a 1/4"-20 UNC coarse thread with Class 3A fit for precise engagement, a shoulder diameter of 5/16" with tolerance of -0.001" to 0.001", and shoulder length of 1/2" with tolerance of -0.005" to 0.005". It meets ASME B18.3 specifications for dimensional consistency and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring safety and environmental responsibility in industrial use.