S-90311A161 1/4"-20 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking: Permanent nylon patch thread locker prevents loosening under dynamic loads, maintaining clamp force in high-vibration environments from -50° to 250°F
• Superior corrosion resistance: 316 stainless steel construction provides excellent protection against harsh chemicals, moisture, and industrial atmospheres
• High mechanical strength: 70,000 psi tensile strength and 35,000 psi shear strength ensure reliable performance in demanding applications
• Precision alignment: Shoulder diameter with tight tolerance control (-0.004" to -0.002") enables accurate component positioning and reduces bearing wear
• Secure installation: Class 3A thread fit and UNC coarse threading provide consistent engagement and reduced cross-threading risk
• Easy installation and removal: Standard hex socket head with 5/32" drive and knurled texture allows for positive tool engagement and manual adjustment
• Industry compliance: Meets ASME B18.3 specifications and environmental regulations including RoHS 3 and REACH for global acceptance

Professional Applications & Engineering Value

This 316 stainless steel shoulder screw with nylon patch thread locker addresses critical challenges in precision assembly applications where vibration resistance and positional accuracy are paramount. The UNC coarse threading and Class 3A thread fit ensure reliable engagement in metal components, while the precisely machined shoulder provides a bearing surface that eliminates the need for separate spacers or bushings. The socket head design with knurled texture facilitates installation in confined spaces common in machinery, automation systems, and precision instruments. The permanent locking feature maintains preload in applications subject to thermal cycling and dynamic stresses, making it ideal for industrial equipment, rotating assemblies, and precision positioning systems where maintenance access is limited.

Specification Summary & Compliance

This shoulder screw features Class 3A thread fit with UNC 1/4"-20 coarse threading, manufactured to ASME B18.3 specifications. The shoulder diameter maintains tight tolerances of -0.004" to -0.002" with shoulder length tolerance of -0.005" to 0.005". The component is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring suitability for global industrial applications requiring strict material and safety standards.