S-91259A504 2-56 ASTM A108 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Strength & Durability: With a tensile strength of 140,000 psi and Rockwell C32 hardness, this shoulder screw withstands high-stress applications, reducing the risk of fastener failure and maintenance downtime.
• Superior Corrosion Resistance: The black oxide finish provides a protective layer against rust and corrosion, extending the screw's service life in harsh industrial environments.
• Precise Shoulder Alignment & Stability: The knurled head and standard shoulder fit ensure secure positioning and prevent rotation during assembly, improving component alignment and operational reliability.
• High-Precision Thread Fit: Class 3A thread fit and UNC coarse threading offer tighter tolerances and easier assembly, minimizing cross-threading and ensuring consistent performance in repetitive applications.
• Easy Installation with Standard Tools: The socket head with 5/64" hex drive allows for quick and secure tightening using common tools, speeding up assembly processes and reducing labor costs.
• Compliance with Industry Standards: Meets ASTM A108, RoHS 3, and REACH regulations, ensuring material quality, environmental safety, and suitability for global supply chains.
• Versatile Material Performance: Made from alloy steel, it delivers optimal strength-to-weight ratio and fatigue resistance, ideal for demanding mechanical and structural applications.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision assembly and heavy-duty machinery. The 2-56 UNC coarse thread with Class 3A fit ensures reliable fastening in components requiring exact thread engagement, reducing the risk of loosening under vibration. The black oxide finish enhances corrosion resistance, making it suitable for environments exposed to moisture or chemicals. The knurled head and precise shoulder diameter provide stable alignment in pulleys, gears, and rotating assemblies, preventing misalignment and wear. With a 140,000 psi tensile strength, it supports high-load applications in automotive, aerospace, and industrial equipment, ensuring long-term performance and reducing maintenance needs. Ideal for applications demanding superior mechanical performance and compliance with rigorous standards.

Specification Summary & Compliance

This shoulder screw adheres to precise dimensional tolerances, including a Class 3A thread fit for superior engagement and a shoulder diameter tolerance of -0.004" to -0.002". It conforms to ASTM A108 for material specifications, ensuring consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), meeting environmental and safety regulations for hazardous substances. These compliances guarantee that the screw is suitable for use in regulated industries and international markets.