S-91327A143 1/4"-20 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with nylon patch thread locker maintains secure fastening from -50° to 250°F, preventing loosening in dynamic applications
• Exceptional corrosion resistance from 18-8 stainless steel construction with passivated finish for long-term reliability in harsh environments
• Precision alignment capability with standard shoulder fit and tight diameter tolerance (-0.004" to -0.002") for accurate component positioning
• High-strength performance delivering 70,000 psi tensile strength and Rockwell B55 hardness for demanding mechanical applications
• Superior thread engagement with Class 3A thread fit and UNC coarse threading for reliable installation and load distribution
• Enhanced grip and torque application through knurled head texture and 5/32" hex drive for secure tool engagement during installation
• Industry compliance assurance meeting ASME B18.3 specifications and RoHS/REACH environmental regulations for quality and safety

Professional Applications & Engineering Value

This 1/4"-20 UNC shoulder screw with nylon patch locking addresses critical vibration and alignment challenges in precision assemblies. The 18-8 stainless steel construction with passivated finish provides excellent corrosion resistance for industrial environments, while the Class 3A thread fit ensures precise engagement in machinery, automation systems, and rotating equipment. The standard shoulder with controlled diameter tolerance enables accurate component positioning in assemblies requiring precise shaft alignment. The nylon patch thread locker maintains fastener integrity across a wide temperature range (-50° to 250°F), making it ideal for applications subject to thermal cycling and vibration, such as motor mounts, gear assemblies, and precision instruments where secure fastening is critical to operational reliability.

Specification Summary & Compliance

This shoulder screw features Class 3A thread fit with 1/4"-20 UNC coarse threading and right-hand direction. The shoulder maintains precise dimensional control with diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005". Manufacturing complies with ASME B18.3 specifications and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards for industrial applications.