S-98892A121 4-40 NAS1291C04M Flange Nuts

Key Features & Benefits at a Glance

• Superior vibration resistance through distorted center lock thread technology, preventing loosening in high-stress environments
• Enhanced durability with A286 stainless steel construction offering excellent corrosion resistance and high-temperature performance
• Precision thread engagement with Class 3B fit ensuring reliable, consistent fastening in critical applications
• Integrated flange design eliminates need for separate washers while providing superior load distribution
• Pre-lubricated for optimal performance with included lubricant reducing installation torque and preventing galling
• Standard external hex drive allows for easy installation with common tools while maintaining 5/32" width for space-constrained applications
• Full regulatory compliance meeting both REACH and RoHS 3 environmental standards for global applications

Professional Applications & Engineering Value

This 4-40 UNC flange locknut delivers exceptional engineering value in demanding applications where vibration resistance and reliability are paramount. The A286 stainless steel construction provides superior strength and corrosion resistance, making it ideal for aerospace applications, precision machinery, and electronic enclosures. The distorted center lock thread technology creates consistent interference along the mating threads, effectively resisting loosening under extreme vibration conditions. The integrated flange design distributes clamping force over a wider surface area (0.206" diameter), reducing stress concentrations and preventing damage to sensitive components. With its Class 3B thread fit and coarse UNC thread spacing, this locknut ensures rapid assembly while maintaining precision alignment in critical fastening applications.

Specification Summary & Compliance

This high-performance flange locknut features precise 4-40 UNC threads with Class 3B thread fit for superior engagement and right-hand threading orientation. Manufactured to NAS1291C04M specifications, the nut maintains dimensional accuracy with a 5/32" width, 1/8" height, 0.206" flange diameter, and 0.01" flange thickness. The product is fully compliant with REACH (EC 1907/2006) and RoHS 3 (2015/863/EU) environmental standards, ensuring safe use in regulated industries. The external hex drive configuration provides reliable tool engagement for consistent installation torque performance.