S-90275A539 1/4"-20 x 5/8" ASME B18.6.3 Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated steel construction, extending service life in demanding industrial environments
• Exceptional tensile strength of 60,000 psi ensures reliable performance under heavy loads and vibration
• Precision Class 2A thread fit provides smooth installation and secure fastening in UNC threaded applications
• Full threading design offers maximum grip length and uniform stress distribution along the entire fastener
• 82° countersink angle enables flush mounting with standard countersunk holes for clean, professional finishes
• Rockwell B70 hardness maintains thread integrity and prevents stripping during repeated installations
• Comprehensive compliance with ASME B18.6.3, RoHS 3, and REACH ensures quality and environmental responsibility

Professional Applications & Engineering Value

This 1/4-20 UNC flat head screw delivers critical engineering advantages for industrial assembly applications where reliable fastening and flush surface mounting are essential. The zinc-plated steel construction provides excellent corrosion protection in manufacturing environments, while the coarse thread spacing and Class 2A fit ensure quick installation and secure holding power in machinery, equipment frames, and structural components. The 82° countersink angle and flat head profile allow for seamless integration into countersunk holes, eliminating protrusions that could interfere with moving parts or create safety hazards. With 60,000 psi tensile strength and Rockwell B70 hardness, these slotted drive screws maintain integrity under vibration and load cycling, making them ideal for maintenance, repair, and OEM applications requiring durable inch system fasteners.

Specification Summary & Compliance

This flat head screw features precision 1/4"-20 UNC threads with Class 2A fit tolerance for consistent performance in standard applications. Manufacturing complies with ASME B18.6.3 specifications for dimensional accuracy and quality assurance. The product meets RoHS 3 (2015/863/EU) compliance for hazardous substance restrictions and REACH (EC 1907/2006) regulations for chemical safety, ensuring environmental responsibility throughout the supply chain.