S-90402A537 1/4"-20 x 1/2" ASME B18.13 Steel Pan Head Phillips Screws with External-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance with the integrated external-tooth lock washer that maintains tightness under dynamic loads
• Enhanced corrosion protection through zinc-plated steel construction, extending service life in harsh environments
• High-strength performance with 60,000 psi tensile strength and Rockwell B69 hardness for demanding applications
• Reliable fastening efficiency due to fully threaded UNC coarse thread design and Class 2A fit for quick assembly
• Secure Phillips drive engagement (No. 3 size) and rounded pan head profile for easy installation and reduced cam-out
• Compliance with industry standards including ASME B18.13, ensuring dimensional accuracy and interchangeability
• Environmental regulation adherence with RoHS 3 and REACH compliance for safe, sustainable use

Professional Applications & Engineering Value

This zinc-plated steel rounded head screw with an external-tooth lock washer is engineered to address critical industrial challenges such as vibration-induced loosening and corrosion in machinery, automotive, and electrical enclosures. The combination of UNC coarse threads and Class 2A thread fit ensures rapid, precise installation while maintaining grip under stress. The fully threaded design provides consistent clamping force along the entire 1/2" length, and the zinc plating offers a protective barrier against moisture and chemicals. Ideal for assembly lines and maintenance, these screws deliver dependable performance where reliability is non-negotiable, reducing downtime and replacement costs.

Specification Summary & Compliance

The screw features a 1/4"-20 UNC coarse thread with Class 2A tolerance for accurate fit, and is manufactured to meet ASME B18.13 specifications. It complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material integrity.