S-91273A173 1/4"-28 Shoulder Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction, ideal for harsh industrial environments and extended service life
• Exceptional mechanical strength with 70,000 psi tensile strength and 35,000 psi minimum shear strength for reliable performance under high stress
• Precision alignment and smooth rotation provided by the 1/4" diameter shoulder with controlled tolerances, reducing wear on mating components
• Secure, non-slip installation thanks to the knurled hex socket head, allowing for high torque application without tool slippage
• Fine-thread reliability with the 1/4"-28 UNF thread and Class 2A fit, ensuring vibration resistance and precise fastening in critical assemblies
• Environmental compliance assurance by meeting RoHS 3 and REACH regulations, making it suitable for global supply chains and sensitive applications
• Optimized for durability with a Rockwell B55 hardness, providing excellent wear resistance and maintaining thread integrity through repeated use

Professional Applications & Engineering Value

This stainless steel shoulder screw is engineered to address common challenges in precision mechanical assemblies, such as misalignment, component wear, and fastener failure under dynamic loads. The 18-8 stainless steel material offers inherent corrosion resistance, crucial for operations in moist or chemically aggressive environments. Its 1/4"-28 UNF fine thread and Class 2A thread fit provide superior holding power and vibration resistance, minimizing the risk of loosening in high-cycle applications. The knurled hex socket head ensures secure tool engagement, facilitating efficient installation in confined spaces while the precisely machined shoulder acts as a pivot, bearing surface, or locator, reducing friction and extending the life of moving parts in machinery, automation systems, and precision instruments.

Specification Summary & Compliance

This shoulder screw adheres to UNF thread standards with a Class 2A thread fit for consistent, precise engagement. 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") ensuring accurate alignment. It is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, confirming the absence of restricted substances and supporting use in regulated industries.