S-90402A540 1/4"-20 x 3/4" ASME B18.13 Steel Pan Head Phillips Screws with External-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance with an integrated external-tooth lock washer that maintains clamping force under dynamic loads
• Enhanced corrosion protection through zinc-plated steel construction for extended service life in demanding environments
• High-strength performance delivering 60,000 psi tensile strength and Rockwell B69 hardness for reliable heavy-duty applications
• Optimized drive efficiency with Phillips No. 3 drive compatibility ensuring secure tool engagement and reduced cam-out risk
• Precise thread engagement through UNC coarse threads with Class 2A fit for quick installation and consistent clamping performance
• Comprehensive compliance meeting ASME B18.13 specifications while being RoHS 3 and REACH compliant for global industrial use
• Full-thread design providing maximum grip length and load distribution across the entire fastener length

Professional Applications & Engineering Value

These zinc-plated steel rounded head screws deliver critical vibration resistance in industrial assemblies where loosening under dynamic loads compromises safety and performance. The external-tooth lock washer bites into mating surfaces, creating permanent resistance to rotational forces in machinery, construction frameworks, and automotive components. With UNC coarse threads and Class 2A fit, installation is accelerated while maintaining precise tolerance control. The Rockwell B69 hardness and 60,000 psi tensile strength ensure these Phillips drive screws withstand extreme mechanical stress without deformation, making them ideal for structural applications where fastener failure is not an option. The combination of fully threaded design and pan head profile provides optimal load distribution while accommodating standard driving tools.

Specification Summary & Compliance

Manufactured to exacting standards with Class 2A thread fit ensuring proper engagement and consistent clamping force. These 1/4"-20 UNC coarse thread screws feature complete compliance with ASME B18.13 manufacturing specifications. The product meets RoHS 3 (2015/863/EU) compliance for hazardous substance restriction and REACH (EC 1907/2006) standards for chemical safety. The zinc-plated steel construction provides corrosion resistance while maintaining the mechanical properties required for industrial fastening applications.