S-91327A156 5/16"-18 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with integrated nylon patch that maintains secure fastening from -50° to 250°F, preventing loosening in dynamic applications
• Exceptional corrosion resistance through 18-8 stainless steel construction and passivated finish for extended service life in harsh environments
• Precision alignment capability with controlled shoulder diameter and length tolerances ensuring accurate component positioning
• High-strength performance delivering 70,000 psi tensile strength and Rockwell B55 hardness for demanding mechanical applications
• Easy installation and removal with hex socket drive and knurled head providing superior grip and torque transmission
• Reliable thread engagement through Class 3A fit UNC coarse threads offering superior wear resistance and assembly efficiency
• Industry compliance assurance meeting ASME B18.3 specifications and environmental regulations for global manufacturing applications

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw delivers critical engineering solutions for precision assembly challenges. The 18-8 stainless steel construction with passivated finish provides exceptional corrosion resistance in manufacturing environments, while the precision-machined shoulder with tight diameter and length tolerances ensures accurate component alignment in rotating assemblies and mechanical linkages. The integrated nylon patch thread locker addresses vibration-induced loosening in machinery, automotive, and industrial equipment applications. With its coarse thread design and Class 3A fit, this fastener enables rapid assembly while maintaining high strength requirements. The combination of hex socket drive and knurled head texture facilitates secure tool engagement in confined spaces, making it ideal for precision instruments, automation systems, and heavy-duty mechanical assemblies where reliability and dimensional accuracy are paramount.

Specification Summary & Compliance

This shoulder screw maintains precision Class 3A thread fit with UNC coarse thread profile (5/16"-18) and controlled shoulder dimensions (diameter tolerance: -0.004" to -0.002", length tolerance: -0.005" to 0.005"). Manufactured in compliance with ASME B18.3 specifications, the fastener meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The mechanical properties include 70,000 psi tensile strength and Rockwell B55 hardness, ensuring consistent performance across industrial applications.