S-91221A181 4-40 x 1" UL 94 HB Plastic Socket Head Screws

Key Features & Benefits at a Glance

• Enhanced Durability & Lightweight Performance: Crafted from glass-filled nylon plastic, this screw offers superior strength-to-weight ratio and excellent resistance to impact and wear in demanding environments.
• Reliable Fastening in Thermal Environments: Withstands a broad operating temperature range from -20° to 230° F, ensuring stable performance and integrity under thermal cycling.
• Precision Thread Engagement: Features a 4-40 UNC coarse thread with a Class 2A fit, providing reliable, vibration-resistant connections and easier assembly in various materials.
• Secure Hex Drive Installation: The 3/32" hex socket drive allows for high-torque application with standard tools, minimizing cam-out and ensuring a tight, flush fit.
• Compliance & Safety Assurance: Meets UL 94 HB flammability standards and is fully compliant with RoHS 3 and REACH regulations, making it safe for use in sensitive electronic and industrial applications.
• Corrosion & Chemical Resistance: The inherent properties of black glass-filled nylon provide excellent resistance to moisture, chemicals, and corrosion, reducing maintenance needs.
• Versatile Fully Threaded Design: The 1" length with full threading ensures maximum grip and adjustability, ideal for applications requiring consistent clamping force along the entire shank.

Professional Applications & Engineering Value

This 4-40 UNC thread socket head cap screw is engineered to address critical challenges in precision assembly, where electrical insulation, weight reduction, and chemical resistance are paramount. The glass-filled nylon plastic construction eliminates galvanic corrosion risks, making it ideal for electronic enclosures, PCB mounting, and automotive components. Its coarse threading and Class 2A fit ensure quick, reliable fastening in plastics and soft metals, reducing assembly time and improving product longevity. The hex drive design allows for secure installation in confined spaces, common in industrial machinery and consumer electronics, providing a robust, non-conductive fastening solution that maintains integrity across a wide temperature range.

Specification Summary & Compliance

This screw adheres to UNC thread standards with a 4-40 thread size and Class 2A thread fit, ensuring precise dimensional accuracy and interchangeability. It is manufactured to meet UL 94 HB specifications for flammability and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for global markets and environmentally conscious applications.