S-91309A501 1/4"-28 x 1/2" ASME B18.2.1, SAE J429 Low-Strength Steel Hex Head Screws
Low-Strength Steel Hex Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Enhanced corrosion resistance with zinc plating, extending service life in demanding industrial environments
- Superior tensile strength of 60,000 psi for reliable load-bearing in critical assemblies
- Precise Class 2A thread fit ensures smooth installation and secure fastening with reduced risk of cross-threading
- Fine UNF threading (28 TPI) provides improved vibration resistance and better tension control compared to coarse threads
- External hex drive design with 7/16" head width enables high-torque application using standard tools
- Full threading along the 1/2" length allows for maximum adjustability and grip in various material thicknesses
- Rockwell B69 hardness rating maintains thread integrity and prevents stripping during repeated use
Professional Applications & Engineering Value
These 1/4"-28 UNF hex head screws deliver exceptional performance in industrial applications where vibration resistance and precise clamping force are critical. The fine thread pitch creates more thread engagement points per inch, significantly reducing loosening under dynamic loads in machinery, automotive components, and electrical enclosures. Manufactured from Grade 2 steel with zinc plating, these fasteners combat corrosion in moderate environments while maintaining the 60,000 psi tensile strength required for structural applications. The external hex drive configuration provides superior torque transmission compared to internal drive types, preventing tool slippage and damaged fastener heads in high-production environments.
Specification Summary & Compliance
This hex head screw features 1/4"-28 UNF fine threads with Class 2A thread fit tolerances per ASME standards, ensuring consistent quality and interchangeability. The fastener complies with ASME B18.2.1 dimensional specifications and SAE J429 Grade 2 mechanical properties. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, making these screws suitable for regulated industries requiring documentation of material restrictions.
