S-90273A107 4-40 x 5/16" ASME B18.6.3 Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated steel construction, ensuring long-term reliability in harsh industrial environments
• High tensile strength of 60,000 psi provides excellent load-bearing capacity for demanding mechanical assemblies
• Rockwell B70 hardness maintains thread integrity and prevents stripping during repeated installations
• Class 2A thread fit ensures smooth, precise engagement with mating components while maintaining manufacturing efficiency
• Standard 82° countersink angle enables flush mounting for clean, professional finishes in visible applications
• Fully threaded design maximizes grip length and distributes clamping force evenly across the entire fastener
• Phillips drive compatibility allows for efficient installation with commonly available industrial tools

Professional Applications & Engineering Value

These 4-40 UNC flat head screws deliver exceptional engineering value through their optimized material and thread design. The zinc-plated steel construction provides essential corrosion protection for industrial equipment, electronic enclosures, and machinery subjected to environmental exposure. The coarse UNC thread profile offers superior resistance to vibration loosening compared to fine-thread alternatives, making these fasteners ideal for applications where mechanical stability is critical. The combination of 60,000 psi tensile strength and Rockwell B70 hardness ensures these screws maintain clamping force under dynamic loads, preventing joint failure in automotive, aerospace, and manufacturing applications. The standard 82° countersink angle and flat head profile create seamless surface finishes while the Phillips drive enables efficient high-volume installation.

Specification Summary & Compliance

This 4-40 UNC flat head screw features precise Class 2A thread fit tolerances per UNC standards, ensuring consistent mating performance. Manufacturing complies with ASME B18.6.3 specifications for dimensional accuracy and mechanical properties. The product meets RoHS 3 (2015/863/EU) compliance for restricted hazardous substances and REACH (EC 1907/2006) regulations for chemical safety, making it suitable for global industrial supply chains. The 5/16" length and fully threaded design provide versatile fastening solutions across multiple industrial applications.