S-91099A478 1/4"-20 x 7/8" 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, ideal for harsh industrial environments
• Exceptional tensile strength of 80,000 PSI ensures reliable performance under high-stress applications
• Precise flush mounting with 82° countersink angle and undercut flat head design for seamless surface integration
• Optimized drive engagement through Phillips No. 3 drive style, reducing cam-out and improving installation efficiency
• Consistent thread performance with UNC coarse threading and Class 2A fit, providing secure fastening in various materials
• Full-length threading enables maximum grip along the entire 7/8" shaft length for enhanced holding power
• Regulatory compliance assurance with RoHS 3 and REACH standards, meeting global environmental and safety requirements

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these 1/4"-20 flat head screws deliver critical performance advantages in machinery assembly, electrical enclosures, and structural frameworks. The passivated 18-8 stainless steel provides exceptional corrosion resistance, significantly extending service life in humid or chemically aggressive environments. The combination of UNC coarse threading and Class 2A thread fit ensures rapid installation with minimal cross-threading risk, while the 82° countersink angle with undercut profile creates flush surfaces that eliminate protrusions in precision equipment. With 80,000 PSI tensile strength and Rockwell B80 hardness, these screws maintain integrity under vibration and dynamic loads, making them ideal for automotive, manufacturing, and marine applications where reliability is paramount.

Specification Summary & Compliance

This flat head machine screw features precise 1/4"-20 UNC coarse threads with Class 2A tolerance for consistent fit and performance. Manufacturing complies with ASME B18.6.3 specifications for dimensional accuracy and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and regulatory acceptance for global industrial supply chains.