S-91385A540 1/4"-20 x 3/4" ASME B18.3, ASTM F912 Set Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with nylon patch thread locker prevents loosening under dynamic loads, maintaining secure fastening in high-stress environments
• Exceptional durability from black-oxide alloy steel construction with Rockwell C45 hardness resists wear and corrosion in demanding industrial applications
• Precise thread engagement with Class 3A UNC coarse threads ensures reliable installation and maximum holding power
• Wide temperature tolerance from -50°F to 250°F allows consistent performance across diverse operating conditions
• Space-saving headless design with hex drive enables flush mounting in confined spaces while providing secure tool engagement
• Cup tip configuration creates positive seating and minimizes surface damage to secured components
• Regulatory compliance meets ASME B18.3 specifications and environmental standards for global industrial use

Professional Applications & Engineering Value

This black-oxide alloy steel set screw delivers critical vibration resistance in machinery, automotive, and manufacturing applications where secure positioning is paramount. The nylon patch locking feature addresses common industrial challenges of fastener loosening caused by constant vibration and thermal cycling, while the UNC Class 3A thread fit provides precise tolerances for repeatable installation torque values. The headless hex drive design offers optimal space utilization in collars, shafts, and pulleys where protruding fasteners are impractical. Engineered for industrial set screw applications requiring both high strength and reliable locking performance, this fastener maintains integrity across temperature extremes from -50°F to 250°F, making it suitable for outdoor equipment, motor assemblies, and precision mechanical systems.

Specification Summary & Compliance

This set screw features 1/4"-20 UNC coarse threads with Class 3A thread fit for precision engagement, manufactured to ASME B18.3 specifications where applicable. The product complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring suitability for global industrial markets. The black-oxide surface treatment on alloy steel substrate provides corrosion resistance while maintaining the Rockwell C45 hardness specification for durable performance.