S-91255A103 4-40 x 1/8" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating, ideal for harsh industrial environments
• Superior torque transmission through 1/16" hex drive design, preventing tool slippage
• Maximum load-bearing capacity with 120,000 psi tensile strength for critical applications
• Precision thread engagement with Class 3A fit ensuring reliable fastening and vibration resistance
• Enhanced durability from Rockwell C39 hardness, maintaining performance under repeated use
• Wide compatibility with UNC coarse threading for faster installation in various materials
• Low-profile rounded head design providing smooth finish and reduced snagging risks

Professional Applications & Engineering Value

These 4-40 UNC thread screws with black-oxide alloy steel construction address critical industrial challenges where corrosion resistance and structural integrity are paramount. The fully threaded design with coarse thread spacing ensures rapid assembly in metal fabrication, electronics enclosures, and machinery components, while the rounded head profile minimizes protrusion in confined spaces. Engineered with Class 3A thread fit, these screws maintain precise clamping force in high-vibration environments, preventing loosening in automotive assemblies or precision equipment. The combination of 120,000 psi tensile strength and hex drive delivers reliable performance in applications demanding both high torque and corrosion protection.

Specification Summary & Compliance

Manufactured to ASME B18.3 and ASTM F835 specifications with Class 3A thread fit precision. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features right-hand UNC coarse threads, 1/8" length, and fully threaded construction for consistent performance across industrial applications.