S-91385A105 4-40 x 3/16" ASME B18.3, ASTM F912 Set Screws

Key Features & Benefits at a Glance

• Secure Vibration Resistance with nylon patch thread locker that maintains locking performance from -50°F to 250°F, preventing loosening in dynamic applications
• Superior Corrosion Protection through black-oxide coating on alloy steel, extending service life in demanding industrial environments
• Precise Thread Engagement with Class 3A thread fit ensuring tight tolerances and reliable fastening in critical assemblies
• High Strength Durability from Rockwell C45 hardened alloy steel construction, providing excellent resistance to wear and deformation
• Space-Saving Design as a headless set screw with hex drive, ideal for confined spaces where protruding fasteners aren't feasible
• Enhanced Grip Performance with cup tip design that creates positive seating and reduces workpiece damage during installation
• Industry Standard Compliance meeting ASME B18.3 specifications for consistent quality and interchangeability

Professional Applications & Engineering Value

This 4-40 UNC set screw delivers exceptional engineering value in precision assembly applications where space constraints and vibration resistance are critical concerns. The black-oxide alloy steel construction combined with Rockwell C45 hardness provides the necessary strength to withstand mechanical stresses while resisting corrosion in industrial environments. The nylon patch thread locker addresses common vibration-induced loosening problems in machinery, automotive components, and electronic enclosures, maintaining secure fastening across a wide temperature range from -50°F to 250°F. The headless hex drive design with 0.050" drive size allows installation in tight spaces where traditional fastener heads would interfere, while the cup tip ensures positive contact and minimal surface damage to secured components. These features make it particularly valuable for precision equipment, manufacturing jigs, and permanent assemblies requiring reliable, long-term fastening solutions.

Specification Summary & Compliance

This set screw features 4-40 UNC coarse threads with Class 3A thread fit for precision engagement and meets ASME B18.3 specifications (ASTM F912) for dimensional accuracy and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental responsibility and workplace safety. Manufacturing follows strict quality standards with right-hand threading, consistent 3/16" length, and proper thread locker application for reliable performance in industrial applications.