S-90403A108 4-40 x 3/8" ASME B18.13 Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer
Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Washer & Nut
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Superior corrosion resistance with zinc-plated steel construction, extending service life in demanding environments
- Reliable vibration resistance through integrated internal-tooth lock washer that maintains clamp load under dynamic conditions
- High-strength performance with 60,000 psi tensile strength and Rockwell B69 hardness for heavy-duty applications
- Quick installation with Phillips No. 1 drive and coarse UNC threads that reduce assembly time
- Precise thread engagement with Class 2A thread fit ensuring consistent fastening performance
- Full-thread design providing maximum grip along the entire 3/8" length for enhanced holding power
- Standard pan head profile offering excellent driver engagement and clean finished appearance
Professional Applications & Engineering Value
These 4-40 UNC zinc-plated steel screws with integrated internal-tooth lock washers deliver critical vibration resistance in industrial assemblies where loosening under dynamic loads poses significant reliability concerns. The coarse thread configuration enables rapid installation in production environments while maintaining Class 2A thread fit precision. The combination of 60,000 psi tensile strength and Rockwell B69 hardness ensures these rounded head screws withstand both static and dynamic stresses in machinery, electronic enclosures, and automotive components. The zinc-plated finish provides essential corrosion protection, while the Phillips drive facilitates efficient installation with standard tools.
Specification Summary & Compliance
This fastener features 4-40 UNC coarse threads with Class 2A thread fit tolerance and fully threaded design. Manufacturing complies with ASME B18.13 specifications for dimensional accuracy and performance. The product meets RoHS 3 (2015/863/EU) compliance for restricted substances and REACH (EC 1907/2006) regulations for chemical safety, ensuring suitability for global industrial applications.
