S-91259A581 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance in high-stress assemblies
• Precision thread engagement with Class 3A UNC coarse threads ensuring secure fastening and vibration resistance in industrial equipment
• Superior corrosion protection through black oxide finish extending service life in demanding environments
• Optimized shoulder design with 5/16" diameter and 3/4" length providing accurate component alignment and rotational stability
• Enhanced installation control with knurled head and 5/32" hex socket drive preventing tool slippage during torque application
• Certified material quality using alloy steel with Rockwell C32 hardness for consistent mechanical properties
• Full regulatory compliance meeting ASME B18.3, RoHS 3 and REACH standards for global industrial applications

Professional Applications & Engineering Value

This alloy steel shoulder screw delivers critical engineering solutions where precision alignment and high strength are paramount. The Class 3A UNC coarse threads provide superior engagement in soft materials and faster assembly in production environments, while the black oxide finish resists corrosion in humid or chemically exposed settings. The precisely machined shoulder with tight diameter and length tolerances ensures accurate component positioning in rotating assemblies, pivot points, and machinery guides. Engineered to ASME B18.3 specifications, these shoulder screws maintain dimensional consistency across high-volume manufacturing applications, from automotive jigs to industrial robotics, where repeated disassembly and reassembly demand durable thread integrity.

Specification Summary & Compliance

Manufactured to ASME B18.3 standards with Class 3A thread fit for precision UNC threading. Shoulder diameter tolerance maintained at -0.004" to -0.002" with shoulder length tolerance of -0.005" to 0.005". Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations. Material certification to ASTM A574 ensures consistent mechanical properties including Rockwell C32 hardness and 140,000 psi tensile strength.