S-90403A109 4-40 x 7/16" ASME B18.13 Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated steel construction for extended service life in demanding environments
• Reliable vibration resistance through integrated internal-tooth lock washers that maintain secure fastening under dynamic loads
• High tensile strength rating of 60,000 psi ensures dependable performance in high-stress applications
• Optimized drive engagement with Phillips No. 1 drive for efficient installation and reduced cam-out risk
• Precision thread compatibility with Class 2A UNC coarse threads for quick assembly and secure fit
• Enhanced bearing surface from pan head design distributes clamping force evenly across joined materials
• Full threading capability provides maximum grip length and adjustment flexibility

Professional Applications & Engineering Value

These zinc-plated steel screws with internal-tooth lock washers deliver critical vibration resistance in industrial equipment, electronic enclosures, and machinery assemblies. The 4-40 UNC coarse threading enables rapid installation while maintaining Class 2A precision fit, reducing assembly time without compromising joint integrity. The combination of 60,000 psi tensile strength and Rockwell B69 hardness ensures these fully threaded Phillips drive screws withstand cyclic loading and environmental exposure. The integrated locking system prevents loosening in applications subject to constant motion or thermal cycling, making them ideal for maintenance-critical operations where fastener failure is not an option.

Specification Summary & Compliance

Manufactured to ASME B18.13 specifications with Class 2A thread fit tolerance for consistent performance. Features UNC coarse threads with 4-40 thread size and 7/16" length. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for global industrial applications.