S-91259A587 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Strength & Durability: With a tensile strength of 140,000 psi and shear strength of 84,000 psi, this shoulder screw provides reliable performance in high-stress applications, reducing the risk of mechanical failure.
• Superior Corrosion Resistance: The black oxide finish on alloy steel offers enhanced protection against rust and wear, extending the screw's service life in harsh industrial environments.
• Precision Thread Fit for Secure Assembly: Class 3A thread fit with 1/4-20 UNC coarse thread ensures tight, accurate engagement, minimizing loosening and improving joint integrity.
• Easy Installation & Removal: The hex drive (5/32") and knurled head design allow for secure tool grip and efficient tightening, saving time during assembly and maintenance.
• Accurate Shoulder Dimensions for Alignment: A precisely machined 1-1/2" shoulder length with tight tolerances provides consistent spacing and alignment for rotating parts, reducing vibration and wear.
• High Hardness for Wear Resistance: Rockwell C32 hardness ensures the screw maintains its shape and threads under repeated use, offering long-term reliability.
• Broad Compliance for Quality Assurance: Meets ASME B18.3 and ASTM A574 standards, along with RoHS 3 and REACH compliance, ensuring safety and environmental responsibility.

Professional Applications & Engineering Value

This shoulder screw is engineered to address common challenges in mechanical assemblies, such as misalignment and component wear. The alloy steel construction, combined with a black oxide finish, provides excellent resistance to corrosion and abrasion, making it ideal for demanding environments like automotive, machinery, and aerospace. The 1/4-20 UNC coarse thread and Class 3A fit deliver precise, secure fastening, while the 1-1/2" shoulder length acts as a reliable pivot or spacer for rotating parts, reducing friction and extending equipment life. Its socket head with hex drive facilitates easy installation in tight spaces, enhancing efficiency in production and maintenance workflows.

Specification Summary & Compliance

This shoulder screw features a 1/4-20 UNC thread with Class 3A fit for high precision, and a shoulder diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005" to ensure consistent performance. It complies with ASME B18.3 and ASTM A574 manufacturing specifications, and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards, guaranteeing safety and regulatory adherence.