S-91771A974 4-40 x 1/8" 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 for long-term reliability in harsh environments
• High tensile strength of 80,000 psi ensures secure fastening under heavy mechanical loads and vibration
• Precision Class 2A thread fit provides smooth installation and consistent engagement in tapped holes
• Undercut flat head design allows for flush mounting without protrusion, ideal for streamlined assemblies
• Phillips drive with No. 1 size offers efficient torque transfer and reduced cam-out risk during installation
• Full threading along the 1/8" length maximizes grip and load distribution across the entire fastener
• Compliance with ASME B18.6.3, RoHS 3, and REACH guarantees industry-standard quality and environmental safety

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered to address critical challenges in precision assembly and machinery. The passivated 18-8 stainless steel material provides excellent resistance to oxidation and chemical exposure, making them ideal for industrial applications in electronics, automotive, and aerospace sectors where durability is paramount. The undercut flat head profile and 100° countersink angle ensure a seamless fit into countersunk holes, eliminating surface protrusions that could interfere with moving parts or aesthetic requirements. With a coarse UNC thread and Class 2A thread fit, these screws offer quick installation and reliable performance in high-vibration environments, reducing maintenance downtime and enhancing operational efficiency.

Specification Summary & Compliance

This product adheres to Class 2A thread fit tolerances per UNC standards, ensuring dimensional accuracy and compatibility with standard tapped holes. Manufacturing and material specifications fully comply with ASME B18.6.3 for consistent quality and performance. Additionally, these screws meet RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulatory requirements, confirming they are free of hazardous substances and safe for use in regulated industries.