S-93310A325 4-40 x 1/8" 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 performance with permanent nylon patch that maintains secure fastening in demanding applications
• Superior corrosion resistance provided by 18-8 stainless steel construction for extended service life in harsh environments
• High-strength reliability with 70,000 psi tensile strength and Rockwell B55 hardness for demanding industrial applications
• Temperature stability with locking performance maintained across a wide operating range from -70° to 250°F
• Precise thread engagement through Class 3A thread fit ensuring consistent, reliable fastening in critical assemblies
• Easy installation and removal with 1/16" hex drive design providing secure tool engagement and efficient maintenance
• Comprehensive compliance meeting major industrial standards including ASME B18.3, ASTM F879, and MIL-DTL-18240

Professional Applications & Engineering Value

This 4-40 UNC coarse thread screw with nylon patch locking technology delivers exceptional vibration resistance in critical assemblies where loosening under dynamic loads is a primary concern. The 18-8 stainless steel construction provides excellent corrosion resistance for harsh industrial environments, while the Class 3A thread fit ensures precise engagement and reliable performance in precision equipment. The rounded button head design offers a low-profile finish with improved aesthetics and reduced snagging risks. Engineered to withstand temperature fluctuations from -70° to 250°F, these screws maintain their locking integrity in applications ranging from electronic enclosures and machinery guards to automotive components and aerospace assemblies where permanent fastening solutions are essential for long-term reliability.

Specification Summary & Compliance

This fully threaded 4-40 UNC coarse thread screw features precision Class 3A thread fit with right-hand threading and standard rounded head profile. Manufactured to exacting specifications including ASME B18.3, ASTM F879, and MIL-DTL-18240 standards. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global industrial markets.