S-91255A102 3-56 x 1/2" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating for extended service life in demanding industrial environments
• Superior torque transmission through hex drive design prevents stripping and ensures reliable fastening
• High tensile strength rating of 120,000 psi provides exceptional load-bearing capacity for critical applications
• Precision Class 3A thread fit ensures tight tolerances and secure mating with compatible components
• Optimized fine threading delivers enhanced vibration resistance and superior holding power
• Rockwell C39 hardness maintains structural integrity under repeated stress and mechanical wear
• Full threading along entire 1/2" length enables maximum adjustability and engagement depth

Professional Applications & Engineering Value

Engineered for precision assemblies requiring high-strength fastening solutions, these black-oxide alloy steel screws address common industrial challenges including vibration loosening, corrosion degradation, and torque management. The UNF fine thread configuration provides superior resistance to vibrational forces in machinery, automotive, and electronic enclosures, while the rounded button head profile offers a low-profile finish that minimizes snagging in confined spaces. The hex drive system ensures maximum torque application without cam-out, making these Class 3A threaded fasteners ideal for precision equipment where dimensional accuracy and reliable performance are critical.

Specification Summary & Compliance

Manufactured to exacting Class 3A thread fit tolerances with UNF fine threading (3-56 size) and full compliance with ASME B18.3 and ASTM F835 manufacturing specifications. These screws meet stringent regulatory requirements including RoHS 3 (2015/863/EU) compliance for hazardous substance restriction and REACH (EC 1907/2006) environmental safety standards, ensuring suitability for global industrial applications.