S-90343A111 4-40 x 5/16" ASME B18.3 18-8 Stainless Steel Thread-Locking Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with 18-8 Stainless Steel construction, ideal for harsh environments and long-term reliability.
• High-strength performance offering 70,000 psi tensile strength and Rockwell B70 hardness for demanding applications.
• Secure, vibration-resistant fastening thanks to the factory-applied epoxy thread locker that cures to full strength in 24 hours.
• Precise, reliable installation with a 3/32" hex drive and standard socket head profile, ensuring tight spaces accessibility and reduced cam-out.
• Superior thread engagement and durability from Class 3A UNC coarse threads, providing excellent wear resistance and quick assembly.
• Wide temperature tolerance with thread locker effective from -60° to 300° F, maintaining hold in extreme operating conditions.
• Full-length threading for maximum grip and adjustability across the entire 5/16" length, enhancing design flexibility.

Professional Applications & Engineering Value

This 18-8 Stainless Steel Socket Head Cap Screw is engineered to address critical challenges in precision assembly and high-stress environments. Its 4-40 UNC coarse thread and Class 3A fit ensure minimal play and superior resistance to loosening under vibration, making it ideal for machinery, automotive, and aerospace components. The integrated epoxy thread locker begins hardening in 15 minutes and reaches full strength within 24 hours, providing a permanent seal that withstands thermal cycling from -60° to 300° F. Combined with a 70,000 psi tensile strength and corrosion-resistant material, this screw reduces maintenance needs and extends service life in industrial fastening applications, from enclosures to heavy-duty equipment.

Specification Summary & Compliance

This screw features a 4-40 UNC coarse thread with Class 3A precision fit for tight tolerances and reliable performance. It is fully threaded, right-hand direction, and complies with ASME B18.3 specifications, ensuring consistency in manufacturing and interchangeability. The epoxy adhesive thread locker meets typical industrial requirements for vibration resistance, and the 18-8 Stainless Steel material supports RoHS and REACH compliance for environmental safety.