S-90298A638 5/16"-18 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish, ideal for harsh industrial environments.
• Precise component alignment ensured by the 3/8" shoulder diameter with tight ±0.001" tolerance, minimizing assembly play.
• High-strength performance delivering 70,000 psi tensile strength and Rockwell B55 hardness for demanding mechanical applications.
• Secure, non-slip installation facilitated by the knurled socket head and 3/16" hex drive, allowing high torque application.
• Reliable thread engagement with Class 3A UNC coarse threads, providing excellent vibration resistance and easy assembly.
• Extended bearing surface from the 3-1/2" shoulder length, supporting rotating parts and reducing wear.
• Compliance with global standards including ASME B18.3, RoHS 3, and REACH, ensuring safety and regulatory acceptance.

Professional Applications & Engineering Value

This 18-8 stainless steel shoulder screw is engineered to address critical alignment and durability challenges in precision machinery. The 3/8" diameter shoulder with minimal tolerance provides an exact locating surface for bearings, gears, and linkages, eliminating misalignment in automated systems and CNC equipment. The passivated finish enhances corrosion resistance, making it suitable for food processing, medical devices, and outdoor applications where moisture is a concern. With its Class 3A thread fit and coarse UNC threading, it ensures rapid assembly and high vibration resistance in automotive and aerospace assemblies. The knurled socket head allows for secure tool engagement, reducing slippage during high-torque fastening in confined spaces, thereby improving maintenance efficiency and equipment uptime.

Specification Summary & Compliance

This shoulder screw adheres to Class 3A thread fit per UNC standards, ensuring precise thread engagement. Manufacturing follows ASME B18.3 specifications for dimensional accuracy, including shoulder diameter tolerance of -0.001" to 0.001" and shoulder length tolerance of -0.005" to 0.005". It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and material restrictions are met for global supply chain integration.