S-90401A537 1/4"-20 x 1/2" Hex Head Screws with Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance with integrated external-tooth lock washers that maintain secure fastening in high-motion environments
• Exceptional tensile strength of 60,000 psi ensures reliable performance under heavy loads and mechanical stress
• Enhanced corrosion protection through zinc-plated steel construction for extended service life in demanding conditions
• Quick installation and removal with standard external hex head design compatible with common wrench tools
• Precise thread engagement with Class 2A UNC coarse threads providing consistent fit and reduced cross-threading risks
• Full-threaded design delivers maximum grip length and holding power across the entire fastener length
• Optimized washer performance with 0.475" OD external-tooth lock washer that bites into surfaces for permanent locking action

Professional Applications & Engineering Value

These 1/4"-20 UNC hex head screws with integrated external-tooth lock washers solve critical vibration-induced loosening problems in industrial equipment, machinery assembly, and automotive applications. The zinc-plated steel construction provides essential corrosion resistance while maintaining Rockwell B70 hardness for durability against wear. The coarse UNC threads ensure rapid installation and reliable performance in materials where fine threads might strip or fail. Engineered with fully threaded design, these fasteners distribute clamping force evenly, preventing joint failure in high-stress environments. The external-tooth lock washer creates positive mechanical locking by embedding into both the fastener head and mounting surface, making these screws ideal for applications subject to constant vibration, thermal cycling, or dynamic loads where maintaining preload is critical for safety and performance.

Specification Summary & Compliance

This hex head screw features precise Class 2A thread fit according to UNC standards with 1/4"-20 coarse threading and right-hand direction. Manufacturing specifications include 1/2" length, 7/16" head width, and integrated external-tooth lock washer with 0.475" OD and 0.028" thickness. The fastener meets RoHS 3 (2015/863/EU) compliance and REACH (EC 1907/2006) regulations, ensuring environmental responsibility and workplace safety standards for global industrial applications.