S-91259A409 8-32 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability with 140,000 psi tensile strength and Rockwell C32 hardness for reliable performance in high-stress applications.
• Precise alignment and reduced wear thanks to the smooth, accurately machined shoulder with tight diameter and length tolerances.
• Superior corrosion resistance provided by the black oxide finish, extending the screw's service life in demanding environments.
• High-reliability fastening ensured by the Class 3A thread fit and coarse UNC thread, offering excellent vibration resistance and ease of assembly.
• Secure, high-torque installation enabled by the socket head with hex drive, allowing for flush mounting and access in confined spaces.
• Guaranteed quality and safety through compliance with ASME B18.3, RoHS 3, and REACH standards, ensuring material and performance consistency.
• Optimized for automated assembly with consistent right-hand threading and standard shoulder fit, streamlining production processes.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision machinery and industrial equipment. The 8-32 UNC coarse thread and Class 3A thread fit provide superior holding power and vibration resistance, preventing loosening in dynamic applications such as rotating assemblies and pivoting joints. The precisely machined 3/16" shoulder length acts as a built-in spacer or pivot point, eliminating the need for additional components and reducing assembly time and potential failure points. The black oxide finish not only enhances corrosion resistance but also reduces galling during installation, which is crucial for maintaining thread integrity in high-cycle manufacturing environments. Combined with its 140,000 psi tensile strength, this screw delivers reliable performance in demanding sectors like automation, aerospace, and heavy machinery, where precision alignment and long-term durability are paramount.

Specification Summary & Compliance

This shoulder screw features a Class 3A thread fit for high-precision assembly, conforming to UNC thread standards with an 8-32 thread size. The shoulder diameter and length are manufactured to tight tolerances (e.g., shoulder diameter: -0.004" to -0.002", shoulder length: -0.005" to 0.005") to ensure consistent performance. It is manufactured in compliance with ASME B18.3 specifications and meets ASTM A574 material standards. The product is also RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring it is free from hazardous substances and safe for use in various industrial and international markets.