S-91771A103 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, ideal for harsh industrial environments
• Exceptional mechanical strength offering 80,000 psi tensile strength and Rockwell B80 hardness for reliable load-bearing performance
• Precision thread engagement with Class 2A UNC coarse threads ensuring secure fastening and vibration resistance
• Flush mounting capability featuring an 82° countersink angle and undercut flat head for seamless surface integration
• Enhanced drive stability with Phillips No. 1 drive style providing consistent torque application and reduced cam-out risk
• Full-threaded design maximizing grip length and distribution of stress across the entire 1/8" length
• Regulatory compliance assurance meeting ASME B18.6.3, RoHS 3, and REACH standards for safe, quality-conscious usage

Professional Applications & Engineering Value

These 4-40 UNC flat head Phillips 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 suitable for electronics, automotive, and marine applications where environmental durability is paramount. The fully threaded coarse spacing and Class 2A thread fit ensure rapid installation and reliable retention under dynamic loads, while the undercut flat head design prevents surface protrusion, protecting adjacent components. With an 82° countersink angle, these screws facilitate smooth flush mounting in sheet metal, plastic housings, and machined parts, reducing assembly time and improving aesthetic finish. Their high 80,000 psi tensile strength supports demanding mechanical fastening needs without compromising on RoHS and REACH compliance for global supply chain integration.

Specification Summary & Compliance

This product adheres to Class 2A thread fit per UNC standards, ensuring dimensional accuracy and interchangeability. Manufacturing and quality are governed by ASME B18.6.3 specifications, covering head style, drive type, and thread geometry. The screws are fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances. Key attributes include a 1/8" length, #1 Phillips drive, and coarse thread spacing, all designed for consistent performance in industrial fastening systems.