S-90403A106 4-40 x 1/4" ASME B18.13 Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance with integrated internal-tooth lock washer to prevent loosening in high-stress applications
• Enhanced corrosion protection through zinc-plated steel construction for extended service life in harsh environments
• High tensile strength rating of 60,000 psi ensures reliable performance under heavy loads and mechanical stress
• Precise installation compatibility with Class 2A thread fit and standard UNC coarse threading for secure fastening
• Optimized drive engagement with Phillips No. 1 drive style and rounded pan head for efficient torque application
• Full-threaded design provides maximum grip length and uniform stress distribution across the entire fastener
• Regulatory compliance assurance meeting ASME B18.13 standards and environmental regulations for industrial use

Professional Applications & Engineering Value

These 4-40 UNC zinc-plated steel screws deliver exceptional engineering value in industrial applications where vibration resistance and corrosion protection are critical. The combination of internal-tooth lock washers and coarse thread spacing creates a reliable fastening solution that maintains integrity in machinery, electronic enclosures, and assembly fixtures. The Rockwell B69 hardness rating ensures durability against wear, while the fully threaded design with Class 2A fit guarantees precise alignment and consistent clamping force. The zinc-plated steel construction provides essential corrosion resistance for demanding environments, making these rounded head Phillips screws ideal for manufacturing equipment, automotive components, and industrial control systems where long-term reliability is paramount.

Specification Summary & Compliance

This fastener features precise Class 2A thread fit with 4-40 UNC coarse threading and right-hand thread direction. Manufacturing specifications comply with ASME B18.13 standards for dimensional accuracy and performance. The product meets RoHS 3 (2015/863/EU) compliance and REACH (EC 1907/2006) regulations, ensuring environmental responsibility and safety in industrial applications. The internal-tooth lock washer provides additional security with 0.268" outer diameter and 0.018" thickness, complementing the 1/4" length screw for complete fastening solutions.