S-94063A537 1/4"-20 x 1/2" ASME B18.6.3 Tamper-Resistant Drilled Spanner Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish for long-lasting performance in harsh environments.
• Enhanced mechanical strength offering 70,000 psi tensile strength and Rockwell B70 hardness for reliable, heavy-duty fastening.
• Precise, secure fit with Class 2A thread fit and UNC coarse threads, ensuring easy assembly and vibration resistance.
• Flush, unobtrusive installation due to the flat head with undercut profile and 82° countersink angle for a smooth surface finish.
• Convenient installation and removal with a drilled spanner drive (No. 14 size), providing a positive grip for torque application.
• Full threading along the 1/2" length for maximum grip and holding power in various material thicknesses.
• Compliance with major industry standards including ASME B18.6.3, RoHS 3, and REACH, ensuring safety and regulatory acceptance.

Professional Applications & Engineering Value

This 1/4"-20 UNC flat head screw is engineered to address critical challenges in industrial assembly, such as the need for high-strength, corrosion-resistant fasteners that maintain integrity under stress. The 18-8 stainless steel material and passivated finish provide exceptional resistance to rust and chemicals, making it ideal for applications in machinery, marine equipment, and outdoor structures. The flat head with undercut and 82° countersink angle allows for a flush mount, reducing snagging and improving aerodynamics in automotive or aerospace components. With a drilled spanner drive, it offers reliable torque transmission in tight spaces, while the fully threaded design ensures uniform load distribution. These features make it a dependable choice for engineers seeking durability, compliance, and ease of maintenance in demanding environments.

Specification Summary & Compliance

This screw adheres to precise dimensional tolerances, including a Class 2A thread fit for consistent assembly and a head diameter tolerance of -0.025" to 0". It conforms to ASME B18.6.3 specifications for mechanical and dimensional integrity, and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free from hazardous substances and suitable for global industrial use.