S-93401A108 4-40 x 3/4" ASTM F835, MS24667-5 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 140,000 psi ensures reliable performance in demanding applications, reducing the risk of fastener failure.
• Cadmium-plated alloy steel construction provides superior corrosion resistance and durability, extending service life in harsh industrial environments.
• Class 3A thread fit offers precise, tight tolerances for secure mating with nuts and threaded holes, minimizing loosening under vibration.
• Fully threaded design allows for maximum grip and load distribution along the entire length, enhancing joint integrity.
• 82° countersink angle with standard flat head profile enables flush mounting for a smooth, aerodynamic surface finish.
• Hex drive style (1/16") facilitates easy installation and removal with standard tools, reducing assembly time and effort.
• Rockwell C39 hardness ensures high wear resistance, maintaining thread integrity through repeated use.

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered to address critical fastening challenges in industrial and heavy-duty settings. Made from cadmium-plated alloy steel, they resist corrosion and wear, ideal for machinery, automotive, and aerospace assemblies where environmental factors threaten fastener integrity. The coarse UNC thread and Class 3A fit provide quick, secure installation with minimal cross-threading risks, while the 82° countersink angle ensures a seamless fit in tapered holes, preventing protrusions that could interfere with moving parts. This combination of high tensile strength and full threading delivers reliable clamping force, solving vibration-induced loosening and enhancing overall structural stability in demanding applications.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including UNC thread form with Class 3A thread fit for tight tolerances, and a length of 3/4" in the inch system. It complies with ASTM F835 specifications (identified as MS24667-5), ensuring consistent quality and performance. The product meets common industry regulations for material safety, such as RoHS and REACH, supporting use in regulated environments without compromising on reliability or durability.