S-95345A426 4-40 x 1/4" ASME B18.13 Stainless Steel Pan Head Phillips Screws with External-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance through integrated external-tooth lock washer that maintains clamping force in dynamic applications
• Excellent corrosion protection with 18-8 stainless steel construction and passivated finish for extended service life in harsh environments
• High strength performance delivering 70,000 psi tensile strength for reliable fastening in demanding applications
• Quick installation and removal with Phillips No. 1 drive and rounded pan head design for efficient assembly operations
• Secure thread engagement with UNC coarse threads and Class 2A fit ensuring consistent performance across multiple installations
• Complete thread coverage with fully threaded design providing maximum grip length in 1/4" applications
• Dual-material reliability combining 18-8 stainless steel screw with 410 stainless steel washer for consistent performance

Professional Applications & Engineering Value

These 4-40 UNC rounded pan head Phillips screws with external-tooth lock washers solve critical vibration-induced loosening problems in industrial equipment and machinery. The 18-8 stainless steel construction with passivated finish provides exceptional corrosion resistance for harsh environments, while the integrated external-tooth lock washer bites into mating surfaces to prevent rotation under dynamic loads. The coarse thread design ensures rapid installation and reliable performance in materials where fine threads might strip. Ideal for vibration-resistant applications in electronics enclosures, machinery guards, and automotive components, these fully threaded screws deliver maximum clamping force across their entire 1/4" length, making them essential for precision assembly operations requiring both security and corrosion protection.

Specification Summary & Compliance

This fastener features Class 2A thread fit with UNC coarse threads (4-40 size) and meets ASME B18.13 manufacturing specifications. The assembly combines an 18-8 stainless steel screw with a 410 stainless steel external-tooth lock washer, both featuring passivated finish for enhanced corrosion resistance. Compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards, ensuring suitability for regulated industries and international markets. The screw delivers 70,000 psi tensile strength and features a Phillips No. 1 drive with standard pan head profile for consistent installation performance.