S-90273A431 1/4"-28 x 1" 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 demanding environments
• High tensile strength of 60,000 psi provides exceptional load-bearing capacity for secure, vibration-resistant assemblies
• Precision Class 2A thread fit guarantees smooth installation and consistent engagement with mating components
• Standard 82° countersink angle enables flush mounting for clean, professional finishes in countersunk applications
• Full threading along the 1" length maximizes grip strength and distributes stress evenly across the entire fastener
• Rockwell B70 hardness rating ensures excellent wear resistance and maintains thread integrity through repeated use
• Phillips drive design with No. 4 size offers familiar, efficient installation with standard driving tools

Professional Applications & Engineering Value

This 1/4"-28 UNF flat head screw delivers critical engineering solutions where flush surface mounting and high-strength fastening are paramount. The zinc-plated steel construction provides essential corrosion protection for industrial equipment, machinery assemblies, and outdoor applications where environmental exposure is a concern. The fine UNF threads offer superior resistance to vibration loosening compared to coarse threads, making these flat head screws ideal for precision instruments, automotive components, and electronic enclosures. The combination of 60,000 psi tensile strength and Rockwell B70 hardness ensures reliable performance under dynamic loads and repeated assembly cycles, while the standard 82° countersink seamlessly integrates with corresponding countersunk holes for aerodynamic and safety-critical applications.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerance per UNF standards with 1/4"-28 fine threading and right-hand orientation. Manufacturing complies with ASME B18.6.3 specifications for dimensional accuracy and performance requirements. The product meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards, ensuring suitability for regulated industries and international markets.