S-91375A558 1/4"-28 x 3/8" ASME B18.3, ASTM F912 Set Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating, extending service life in harsh industrial environments
• Exceptional holding power achieved through Class 3A thread fit precision, preventing loosening under vibration
• High-strength durability from alloy steel construction with Rockwell C45 hardness for heavy-duty applications
• Secure installation with hex drive design providing positive torque transmission and slip-resistant engagement
• Precise component positioning through cup point tip that creates permanent seating indentations
• Space-saving design with headless construction ideal for confined spaces and flush mounting requirements
• Regulatory compliance assurance meeting ASME B18.3, RoHS 3, and REACH standards for global industrial use

Professional Applications & Engineering Value

This black-oxide alloy steel set screw delivers critical engineering solutions for applications requiring permanent positioning and vibration resistance. The Class 3A thread fit ensures precise engagement with mating components, eliminating play in precision assemblies while the UNF fine threads provide superior load distribution compared to coarse thread alternatives. The cup point design bites into shaft materials, creating reliable mechanical locking that withstands rotational forces in pulleys, gears, and collars. Particularly valuable in industrial machinery, automotive systems, and precision equipment, this fastener maintains integrity under continuous stress while the black-oxide surface treatment resists corrosion in demanding environments. The combination of Rockwell C45 hardness and controlled torque application through the hex drive prevents stripping during installation, ensuring consistent performance across production runs.

Specification Summary & Compliance

Manufactured to exacting ASME B18.3 specifications with Class 3A thread fit tolerance for precision assembly. Features 1/4"-28 UNF fine threads with right-hand direction and 3/8" length dimensions. The black-oxide alloy steel construction provides consistent performance while meeting RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance requirements for environmentally responsible manufacturing and use in regulated industries.