S-93310A539 1/4"-20 x 5/8" ASME B18.3, ASTM F879, MIL-DTL-18240 Thread-Locking Stainless Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Vibration-Resistant Locking: Integrated nylon patch ensures reliable thread locking, preventing loosening under dynamic loads and reducing maintenance needs.
• Superior Corrosion Resistance: Made from 18-8 stainless steel, offering excellent durability in harsh environments and prolonged service life.
• High Tensile Strength: Withstands up to 70,000 psi, providing secure fastening for high-stress industrial applications.
• Easy and Secure Installation: Hex drive design allows for efficient torque application with standard tools, minimizing installation time.
• Precision Thread Fit: Class 3A UNC coarse threads ensure tight, accurate engagement for consistent performance.
• Wide Temperature Tolerance: Nylon patch remains effective from -70° to 250°F, suitable for diverse operating conditions.
• Rounded Button Head Profile: Reduces surface protrusion and snagging risks, enhancing safety and aesthetics in assembled products.

Professional Applications & Engineering Value

This nylon patch locking rounded head screw is engineered to address critical challenges in machinery, automotive, and electronics assembly where vibration-induced loosening can lead to equipment failure. The 18-8 stainless steel construction provides inherent corrosion resistance, ideal for outdoor or chemically exposed settings. Its hex drive and UNC coarse threads facilitate quick, reliable installations, while the Class 3A thread fit ensures minimal backlash and superior load distribution. Commonly used in securing panels, brackets, and components subject to thermal cycling or motion, this fastener delivers long-term reliability without frequent retightening, streamlining maintenance schedules and reducing downtime.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 3A fit for high precision. It is fully threaded and right-hand oriented, with dimensions including a 5/8" length, 0.437" head diameter, and 5/32" hex drive. Manufacturing and performance adhere to ASME B18.3, ASTM F879, and MIL-DTL-18240 specifications. The product is RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, ensuring environmental safety and regulatory alignment for global industrial use.