S-90403A537 1/4"-20 x 1/2" ASME B18.13 Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance with an integrated internal-tooth lock washer that maintains tight, secure connections in high-motion environments.
• Exceptional durability and corrosion resistance thanks to zinc-plated steel construction, ensuring long service life in harsh industrial conditions.
• High tensile strength of 60,000 psi and Rockwell B69 hardness for reliable performance under heavy loads and stress.
• Effortless installation and removal with a No. 3 Phillips drive and fully threaded UNC coarse thread design, reducing assembly time.
• Precise Class 2A thread fit ensures consistent, reliable engagement with mating components, minimizing cross-threading risks.
• Comprehensive compliance with ASME B18.13 standards, RoHS 3, and REACH regulations for safe, quality-assured use in global markets.
• Versatile pan head profile provides a low-profile, rounded finish that distributes clamping force evenly and resists surface damage.

Professional Applications & Engineering Value

Engineered for demanding industrial settings, these zinc-plated steel screws with an internal-tooth lock washer address critical challenges like vibration-induced loosening and corrosion. The 1/4"-20 UNC coarse thread and fully threaded design ensure rapid installation and robust holding power in machinery, automotive assemblies, and electrical enclosures. The Phillips pan head offers a secure drive interface, while the integrated washer eliminates the need for separate components, streamlining inventory and reducing assembly errors. Ideal for heavy-duty fastening in environments where reliability and regulatory compliance are non-negotiable, these screws deliver consistent performance backed by 60,000 psi tensile strength and industry-standard certifications.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 2A fit for precise dimensional accuracy and reliable mating. It meets ASME B18.13 manufacturing specifications and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and global market suitability. The internal-tooth lock washer, made from zinc-plated steel, enhances locking performance without additional components.