S-93310A106 4-40 x 1/4" 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 performance with permanent nylon patch locking that prevents loosening under dynamic loads
• Superior corrosion resistance thanks to 18-8 stainless steel construction for long-term reliability in harsh environments
• High-strength durability with 70,000 psi tensile strength and Rockwell B55 hardness for demanding applications
• Wide temperature tolerance maintaining locking integrity from -70° to 250°F for extreme operating conditions
• Precise thread engagement with Class 3A fit and UNC coarse threads ensuring secure fastening and easy installation
• Streamlined installation featuring hex drive design for efficient torque application and rounded button head profile
• Industry compliance assurance meeting multiple military and industrial standards for quality and safety

Professional Applications & Engineering Value

These 4-40 UNC thread nylon patch locking screws provide critical vibration resistance in demanding industrial applications where fastener failure is not an option. The permanent nylon patch locking technology creates consistent friction that maintains clamp load under continuous vibration, eliminating the need for secondary locking mechanisms. Made from 18-8 stainless steel, these fasteners offer excellent corrosion resistance while the rounded button head design provides a low-profile finish that reduces snagging hazards. The coarse UNC threading ensures rapid installation and superior holding power in various materials, making them ideal for electronics enclosures, machinery guards, automotive components, and aerospace assemblies where reliability and regulatory compliance are paramount.

Specification Summary & Compliance

This 1/4" length screw features precision Class 3A thread fit with 4-40 UNC coarse threading and full threading along the shank. Manufactured to exacting standards including ASME B18.3, ASTM F879, and MIL-DTL-18240 specifications. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global markets. The hex drive measures 1/16" with a head diameter of 0.213" and head height of 0.059" for consistent installation across applications.