S-92805A108 4-40 x 3/8" ASME B18.3, ASTM F879, MIL-DTL-18240 Stainless Steel Thread-Locking Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with permanent nylon patch that maintains integrity across a wide temperature range from -65° to 250°F
• Superior corrosion resistance thanks to 18-8 stainless steel construction, ideal for harsh industrial environments
• Exceptional mechanical strength with 70,000 psi tensile strength and Rockwell B55 hardness for demanding applications
• Precision thread engagement with Class 3A fit and UNC coarse threading ensuring reliable fastening performance
• Optimized flush mounting featuring standard 82° countersink angle and flat head design for seamless surface integration
• Enhanced installation control through hex drive design providing secure tool engagement during assembly
• Industry compliance assurance meeting multiple military and industrial specifications for quality verification

Professional Applications & Engineering Value

This 4-40 UNC flat head screw delivers critical vibration resistance in industrial machinery, electronic enclosures, and precision equipment where loosening under dynamic loads poses significant reliability concerns. The nylon patch locking mechanism creates permanent friction that eliminates the need for secondary locking components, streamlining assembly while maintaining performance across extreme temperature fluctuations. Manufactured from 18-8 stainless steel, these screws provide inherent corrosion resistance that extends service life in humid or chemically aggressive environments. The combination of Class 3A thread fit with coarse UNC threading ensures rapid installation and secure fastening in various materials, while the flat head design with standard 82° countersink enables flush mounting for applications requiring aerodynamic surfaces or preventing snagging hazards.

Specification Summary & Compliance

This fastener features precision 4-40 UNC threads with Class 3A fit and coarse thread spacing, manufactured to exacting dimensional standards. The screw meets ASME B18.3, ASTM F879, and MIL-DTL-18240 specifications, ensuring consistent quality and performance. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations confirms environmental responsibility and material safety standards for global industrial applications.