S-91306A315 4-40 x 3/8" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 120,000 psi ensures reliable performance under high-stress conditions, reducing failure risks in demanding applications.
• Class 3A thread fit provides tighter tolerances for superior engagement and vibration resistance, minimizing loosening in dynamic environments.
• Zinc-plated alloy steel construction offers excellent corrosion resistance, extending service life in harsh industrial settings.
• Fully threaded design maximizes holding power and load distribution, ideal for securing components where full thread contact is critical.
• Hex drive (1/16") with rounded button head allows for easy installation and a low-profile finish, reducing snagging and improving aesthetics.
• Rockwell C39 hardness enhances durability and wear resistance, maintaining thread integrity through repeated use.
• Coarse UNC threads enable quick assembly and better performance in materials prone to stripping or where rapid installation is needed.

Professional Applications & Engineering Value

These 4-40 UNC rounded head screws are engineered to address common industrial challenges, such as vibration-induced loosening and corrosion in machinery assemblies. The zinc-plated alloy steel material provides a protective barrier against moisture and chemicals, making them suitable for automotive, electronics, and heavy equipment applications. With a Class 3A thread fit and coarse UNC thread type, they ensure precise, secure fastening in soft metals or plastics, reducing the risk of cross-threading and improving assembly efficiency. The fully threaded design and high tensile strength offer consistent clamping force, essential for maintaining structural integrity in dynamic loads. Ideal for button head screw uses where a smooth, low-profile finish is required, these screws deliver reliability in OEM and MRO settings, streamlining maintenance and reducing downtime.

Specification Summary & Compliance

This product adheres to precise dimensional standards, including Class 3A thread fit for tight tolerances and UNC coarse threads with a size of 4-40. Manufactured in compliance with ASME B18.3 and ASTM F835 specifications, it ensures consistent quality and performance. Additionally, it meets regulatory requirements such as RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) for environmental and safety standards, supporting sustainable industrial practices.