S-91099A104 2-56 x 1/4" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with passivated 18-8 stainless steel construction, ensuring long-term reliability in harsh environments
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for demanding applications
• Precise flush installation through undercut flat head design with 82° countersink angle for seamless surface finishing
• Reliable fastening performance with Class 2A thread fit and fully threaded UNC coarse threads for secure connections
• Enhanced driving efficiency with Phillips No. 1 drive that prevents cam-out during installation
• Industry-standard compliance meeting ASME B18.6.3 specifications for consistent quality and interchangeability
• Environmental responsibility with RoHS 3 and REACH compliance for sustainable manufacturing practices

Professional Applications & Engineering Value

These 2-56 UNC flat head screws deliver critical engineering advantages for precision assembly applications where surface finish and corrosion resistance are paramount. The passivated 18-8 stainless steel construction provides excellent protection against oxidation and chemical exposure, making them ideal for electronics enclosures, instrumentation panels, and aerospace components. The undercut flat head profile with 82° countersink angle ensures flush mounting without protrusion, eliminating snag points while maintaining structural integrity. With fully threaded coarse UNC threads and Class 2A fit, these screws offer superior holding power in thin materials and blind holes, reducing the risk of cross-threading during high-volume assembly operations. The combination of 80,000 psi tensile strength and controlled hardness (Rockwell B80) prevents stripping while maintaining sufficient ductility for vibration-resistant fastening in dynamic environments.

Specification Summary & Compliance

This 1/4" flat head screw features precise Class 2A thread fit with UNC coarse threading (2-56) and right-hand thread direction, manufactured to exacting dimensional standards. The fastener complies with ASME B18.6.3 specifications for dimensional consistency and mechanical properties. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring restricted substance compliance for global markets. The product maintains 82° countersink angle and fully threaded construction as specified, with all critical dimensions including head diameter (0.162") and head height (0.036") controlled to deliver reliable performance in precision applications.