S-91375A731 1/2"-20 x 5/8" ASME B18.3, ASTM F912 Set Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide finish, extending service life in demanding industrial environments
• Precise thread engagement with Class 3A fit and UNF fine threads for vibration-resistant, secure fastening
• High torque capability through 1/4" hex drive design, enabling efficient installation in confined spaces
• Exceptional material strength from Rockwell C45 hardened alloy steel, preventing deformation under heavy loads
• Reliable positioning with cup point tip that creates permanent seating in shafts and collars
• Space-saving design as headless set screw for applications with limited clearance requirements
• Regulatory compliance meeting major industrial standards for global manufacturing applications

Professional Applications & Engineering Value

This black-oxide alloy steel set screw delivers critical performance in precision assembly applications where vibration resistance and positional stability are paramount. The Class 3A thread fit ensures minimal backlash in high-speed rotating equipment, while the UNF fine threading provides superior clamping force distribution compared to coarse threads. The cup point design bites into mating surfaces, creating permanent alignment in pulley systems, gear assemblies, and coupling applications. With Rockwell C45 hardness, this fastener maintains its structural integrity under cyclic loading conditions common in automotive, aerospace, and heavy machinery components. The headless configuration with 1/4" hex drive allows installation in tight spaces where conventional socket heads would interfere, making it ideal for precision instruments and compact mechanical systems.

Specification Summary & Compliance

Manufactured to ASME B18.3 specifications with Class 3A thread tolerance for precision fit applications. Features 1/2"-20 UNF fine threads with right-hand direction and 0.5" thread diameter. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring suitability for global industrial markets. The 5/8" length provides optimal engagement depth for secure fastening in various material thicknesses.