S-90402A110 4-40 x 1/2" ASME B18.13 Steel Pan Head Phillips Screws with External-Tooth Lock Washer
Steel Pan Head Phillips Screws with External-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
- Vibration-resistant locking with an external-tooth lock washer prevents loosening under dynamic loads, ensuring long-term joint integrity
- Enhanced corrosion protection from zinc-plated steel construction extends service life in demanding industrial environments
- High tensile strength (60,000 psi) and Rockwell B69 hardness provide reliable performance under substantial mechanical stress
- Coarse UNC threading enables faster installation and superior grip in softer materials or rapid assembly applications
- Class 2A thread fit ensures consistent, trouble-free mating with standard nuts and threaded components
- Pan head design with Phillips No. 1 drive offers a low-profile, flush finish while accommodating common driving tools
- Full threading along the 1/2" length maximizes adjustability and clamping force distribution across the entire fastener
Professional Applications & Engineering Value
Engineered for vibration-prone industrial environments, these 4-40 UNC zinc-plated steel screws integrate an external-tooth lock washer that bites into mating surfaces to prevent rotational loosening—critical in machinery, automotive assemblies, and electronic enclosures subject to constant motion. The coarse thread configuration reduces cross-threading risks during high-speed installation while maintaining strong holding power in sheet metal, plastics, and soft alloys. Combined with 60,000 psi tensile strength and a corrosion-resistant zinc-plated finish, this fully threaded pan head screw delivers reliable performance where vibration resistance, durability, and compliance with industry standards are non-negotiable.
Specification Summary & Compliance
This rounded head screw features 4-40 UNC coarse threads with Class 2A thread fit for consistent dimensional accuracy. Manufactured to ASME B18.13 specifications and supplied with an integrated external-tooth lock washer, it complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring suitability for global industrial supply chains.
