S-91273A608 5/16"-18 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with 18-8 stainless steel construction, ideal for harsh industrial environments and extended service life.
• High tensile and shear strength (70,000 psi tensile, 35,000 psi min shear) ensures reliable performance under heavy loads and vibration.
• Superior grip and tool engagement from the knurled socket head and hex drive, preventing cam-out and enabling secure installation.
• Precise thread fit (Class 2A) and coarse UNC threads for easier assembly, reduced cross-threading risk, and consistent clamping force.
• Enhanced durability and wear resistance with a black oxide finish, providing a protective layer and a sleek, non-reflective appearance.
• Accurate shoulder dimensions with tight tolerances for precise alignment of components like gears, pulleys, and linkages.
• Compliance with major regulations including RoHS 3 and REACH, ensuring environmental safety and suitability for global markets.

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw is engineered to address critical alignment and pivot point requirements in demanding applications. The 18-8 stainless steel material provides excellent resistance to rust and corrosion, making it suitable for food processing, marine, and outdoor equipment. The 3-1/2" shoulder length acts as a precise datum for rotating parts like bearings and cams, reducing wear and maintaining concentricity. Combined with the black oxide finish, it offers added protection against galling and seizing. The knurled socket head ensures a positive grip with standard hex tools, speeding up assembly in automated or manual production lines while preventing slippage that can damage the fastener or workpiece. This design is ideal for machinery, automotive assemblies, and conveyor systems where reliable fastening and repeatable positioning are paramount.

Specification Summary & Compliance

This shoulder screw features a Class 2A thread fit per UNC standards, ensuring interchangeability and smooth assembly. The shoulder diameter tolerance is -0.004" to -0.002", and the shoulder length tolerance is -0.005" to 0.005" for precise component alignment. Manufactured from 18-8 stainless steel with a hardness of Rockwell B55, it meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance, confirming it is free of restricted hazardous substances and safe for industrial use.