S-91381A363 5/16"-24 x 5/8" ASME B18.3 Set Screws

Key Features & Benefits at a Glance

• Superior holding power with Class 3A thread fit for reliable, vibration-resistant fastening in demanding applications.
• Enhanced surface protection with a soft brass tip that prevents marring and damage to expensive components.
• Exceptional durability from Black-Oxide Alloy Steel offering excellent corrosion resistance and a Rockwell C28 hardness for long service life.
• Precise and secure installation using a 5/32" hex drive, providing a positive grip and high torque capability in a headless design.
• Guaranteed interchangeability and performance, manufactured to meet the stringent dimensional requirements of ASME B18.3.
• Safe for regulated environments, fully compliant with RoHS 3 and REACH regulations.
• Optimized for fine-thread applications with a 5/16"-24 UNF thread, offering a larger number of threads per inch for finer adjustments and improved strength.

Professional Applications & Engineering Value

This 5/16"-24 UNF set screw is engineered to solve critical challenges in precision assembly and motion control systems. The headless design and hex drive allow for installation in confined spaces where a protruding head is not feasible, making it ideal for securing collars, gears, and pulleys on shafts. The Class 3A thread fit provides a tighter tolerance than commercial-grade fasteners, drastically reducing the risk of loosening under vibration—a common failure point in machinery. The integrated brass soft tip is a key engineering feature that applies holding force without galling or damaging the shaft surface, preserving the integrity of high-value components. Made from Black-Oxide Alloy Steel, it delivers the necessary Rockwell C28 hardness for strength while the black-oxide finish adds a layer of corrosion resistance, ensuring reliable performance in various industrial applications.

Specification Summary & Compliance

This set screw adheres to a Class 3A thread fit for superior dimensional accuracy and is manufactured according to the ASME B18.3 specification for socket set screws. The thread is a 5/16"-24 UNF (Unified National Fine) with a right-hand direction. The product is confirmed to be compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free of restricted hazardous substances for safe use in global markets.