S-91375A103 4-40 x 1/8" ASME B18.3, ASTM F912 Set Screws

Key Features & Benefits at a Glance

• Superior holding strength with Class 3A thread fit for precise, vibration-resistant fastening in demanding applications.
• Enhanced corrosion resistance from the black-oxide finish on alloy steel, extending service life in various industrial environments.
• High durability and wear resistance due to Rockwell C45 hardness, ensuring long-term performance under mechanical stress.
• Secure and efficient installation with the 0.050" hex drive, allowing for high torque application without head protrusion.
• Effective grip and minimal surface damage from the cup tip design, ideal for securing components on shafts and axles.
• Reliable coarse UNC threading for quicker assembly and reduced cross-threading risk in right-hand applications.
• Compliance with global standards including ASME B18.3, RoHS 3, and REACH, ensuring safety and environmental responsibility.

Professional Applications & Engineering Value

This 4-40 UNC set screw is engineered to address critical challenges in precision assembly and machinery. The black-oxide alloy steel construction provides excellent resistance to rust and wear, making it suitable for automotive, aerospace, and manufacturing equipment where exposure to oils and moisture is common. Its headless design with a hex drive allows for flush mounting in confined spaces, preventing interference and improving aesthetics. The Class 3A thread fit and coarse thread spacing ensure tight tolerances and rapid installation, reducing the risk of loosening under vibration. Coupled with a cup tip, it offers superior gripping force on rotating shafts without marring surfaces, enhancing reliability in motion control systems. This screw meets ASME B18.3 specifications, delivering consistent performance for engineers seeking durable, compliant fastening solutions.

Specification Summary & Compliance

This set screw adheres to Class 3A thread fit per UNC standards, ensuring high precision and interchangeability. It conforms to ASME B18.3 manufacturing specifications and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing it is free from hazardous substances and safe for industrial use worldwide.