S-91099A453 1/4"-20 x 3/4" 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, ideal for harsh environments and long-term reliability.
• Exceptional mechanical strength offering 80,000 PSI tensile strength and Rockwell B80 hardness for demanding applications.
• Optimized flush mounting featuring an 82° countersink angle and undercut flat head design for a clean, secure fit.
• Efficient installation and removal with a Phillips No. 3 drive, ensuring compatibility with common tools and reducing assembly time.
• Reliable coarse threading using UNC 1/4"-20 threads for quick engagement and strong holding power in various materials.
• Precision thread fit with Class 2A tolerance, providing consistent performance and ease of use in automated or manual assembly.
• Full regulatory compliance meeting ASME B18.6.3, RoHS 3, and REACH standards for safe, industry-approved use.

Professional Applications & Engineering Value

This flat head Phillips machine screw is engineered to address critical challenges in industrial settings, such as vibration loosening and material degradation. The passivated 18-8 stainless steel provides excellent resistance to rust and chemicals, making it suitable for outdoor equipment, marine hardware, and food processing machinery where moisture exposure is common. Its UNC coarse threading and fully threaded design ensure rapid installation and high pull-out strength in metals, plastics, and composites. The 82° countersink angle and undercut head profile allow for a flush finish, reducing snag risks and improving aerodynamic or aesthetic surfaces in automotive, aerospace, and electronics assemblies. By combining robust tensile strength with precise Class 2A thread fit, this screw minimizes the risk of strip-out and maintains clamp load under dynamic stresses, enhancing overall system integrity.

Specification Summary & Compliance

This product adheres to strict dimensional and performance criteria, including a Class 2A thread fit for consistent engagement and UNC coarse threads (1/4"-20) per standard specifications. Manufacturing follows ASME B18.6.3 for machine screws, ensuring reliability in industrial fastening. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of hazardous substances and supporting environmental safety in global supply chains.