S-91259A501 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional shear resistance with 84,000 psi minimum shear strength for reliable performance under heavy loads
• Precision thread fit with Class 3A tolerance ensuring consistent, vibration-resistant fastening in demanding applications
• Superior corrosion protection through black oxide finish extending service life in harsh industrial environments
• Enhanced grip and torque application with knurled socket head and 5/32" hex drive preventing tool slippage
• High-strength construction from alloy steel with Rockwell C32 hardness and 140,000 psi tensile strength
• Accurate shoulder positioning with controlled diameter and length tolerances for precise component alignment
• Regulatory compliance assurance meeting ASME B18.3, RoHS 3, and REACH standards for quality and safety

Professional Applications & Engineering Value

This alloy steel shoulder screw delivers critical engineering value in precision assembly applications where component alignment and high-strength fastening are paramount. The 1/4"-20 UNC coarse threads with Class 3A fit provide exceptional engagement stability in machinery, automotive, and industrial equipment, resisting vibration-induced loosening. The precisely manufactured shoulder diameter and controlled tolerances ensure accurate bearing surfaces for rotating components, eliminating misalignment issues. The black oxide finish offers reliable corrosion resistance in environments exposed to moisture and chemicals, while the knurled socket head with hex drive enables secure torque application in confined spaces. These features combine to solve common industrial fastening challenges including precision positioning, vibration resistance, and durability requirements.

Specification Summary & Compliance

This shoulder screw maintains Class 3A thread fit per UNC standards with precise dimensional control including shoulder diameter tolerance of -0.004" to -0.002" and shoulder length tolerance of -0.005" to 0.005". Manufactured to ASME B18.3 specifications using ASTM A574 alloy steel, it delivers consistent mechanical properties including Rockwell C32 hardness and 140,000 psi tensile strength. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and regulatory adherence for industrial applications worldwide.