S-93691A390 1/4"-20 MS51576-27, NASM51576 Shoulder Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish, ideal for harsh environments and extended service life.
• Exceptional mechanical strength offering 70,000 psi tensile strength and Rockwell B55 hardness for reliable performance under high-stress conditions.
• Precise alignment and location ensured by the smooth, accurately machined 5/16" diameter shoulder with tight tolerances for minimal play.
• Easy and secure installation using the standard hex socket drive (5/32"), preventing cam-out and allowing for high torque application.
• Wide compatibility and reliable fastening with standard 1/4"-20 UNC coarse threads and Class 2A fit, ensuring consistent engagement.
• Compliance with stringent industry standards including MS51576-27 (NASM51576), guaranteeing quality and interchangeability.
• Environmentally responsible manufacturing confirmed by full compliance with RoHS 3 and REACH regulations.

Professional Applications & Engineering Value

This precision shoulder screw is engineered to solve critical alignment and pivot point challenges in demanding assemblies. The 18-8 stainless steel material, enhanced by a passivated finish, provides excellent resistance to oxidation and corrosion, making it suitable for applications in machinery, automotive, and aerospace sectors where exposure to moisture and chemicals is a concern. The integral 5/16" shoulder acts as a precise datum for locating gears, bearings, or linkages, eliminating the need for separate spacers and reducing assembly complexity. Combined with the high tensile strength and the reliable UNC coarse thread, this fastener ensures a robust and durable connection that maintains integrity under dynamic loads and vibration, delivering long-term engineering value and reduced maintenance.

Specification Summary & Compliance

This shoulder screw features a 1/4"-20 UNC thread with a Class 2A fit for standard tolerance and easy assembly. The shoulder diameter is precisely held at 5/16" with a tolerance of -0.001" to 0", and the shoulder length is 5/8" with a 0" to 0.002" tolerance. The product is manufactured to meet the exacting requirements of specification MS51576-27 (NASM51576). It is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring it adheres to important environmental and safety regulations.