S-91263A178 1/4"-28 x 1 1/4" ASME B18.3 Alloy Steel Hex Drive Flat Head Screws
Alloy Steel Hex Drive Flat 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
- Superior corrosion resistance with zinc-plated alloy steel construction for extended service life in demanding environments
- Exceptional load-bearing capability with 120,000 PSI tensile strength and Rockwell C32 hardness for high-stress applications
- Precision thread engagement with Class 3A fit and UNF fine threads ensuring vibration resistance and secure fastening
- Optimal flush mounting with standard 82° countersink angle and flat head design for seamless surface integration
- Enhanced installation efficiency with 5/32" hex drive providing reliable torque transmission and reduced slippage
- Full regulatory compliance meeting ASME B18.3 standards, RoHS 3, and REACH for global industrial acceptance
- Complete thread coverage with 1-1/4" fully threaded design maximizing grip length and connection stability
Professional Applications & Engineering Value
These 1/4"-28 UNF flat head screws deliver critical engineering solutions where flush surface mounting and high tensile strength are paramount. The zinc-plated alloy steel construction provides essential corrosion protection for machinery, automotive assemblies, and industrial equipment exposed to harsh conditions. The fine thread spacing and Class 3A thread fit ensure superior vibration resistance in dynamic applications, while the 82° countersink angle enables perfect seating in precision-machined components. With fully threaded design and hex drive compatibility, these screws offer reliable performance in critical joints requiring maximum clamping force and easy installation with standard tools.
Specification Summary & Compliance
Manufactured to exacting ASME B18.3 specifications with Class 3A thread fit precision and UNF fine thread standards. Features include 1/4"-28 thread size, 1-1/4" length, and 82° countersink angle. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global industrial markets.
