S-90069A217 0.318" ID x 0.599" OD ASME B18.21.1 Countersunk External-Tooth Lock Washers

Key Features & Benefits at a Glance

• Superior vibration resistance through external tooth design that bites into mating surfaces, preventing loosening under dynamic loads
• Enhanced corrosion protection with black oxide steel finish, extending service life in demanding industrial environments
• Perfect flush mounting with 82° countersink angle that matches standard screw heads for smooth, professional installations
• Exceptional durability with Rockwell C40 hardness rating, maintaining tooth integrity and locking performance through repeated use
• Reliable dimensional consistency with precise 0.318" ID and 0.599" OD ensuring proper fit for 5/16" fasteners
• Industry-standard compliance meeting ASME B18.21.1 specifications for guaranteed performance and interchangeability
• Environmental responsibility with RoHS 3 and REACH compliance, safe for various industrial applications

Professional Applications & Engineering Value

This countersunk external tooth lock washer delivers critical vibration resistance in high-stress mechanical assemblies where fastener security is paramount. The black oxide steel construction provides essential corrosion resistance while the precisely engineered external teeth create multiple biting points that dig into both the fastener head and mating surface. This design prevents rotational slippage and maintains clamp load in vibrating machinery, automotive systems, and heavy equipment. The 82° countersink angle ensures seamless integration with standard fastener heads, eliminating protrusions while the Rockwell C40 hardness maintains tooth sharpness through multiple installation cycles. Ideal for industrial maintenance, manufacturing equipment, and transportation applications where reliable vibration-resistant fastening solutions are essential for operational safety and reduced maintenance intervals.

Specification Summary & Compliance

This 5/16" external tooth lock washer features precise dimensional specifications including 0.318" inner diameter, 0.599" outer diameter, and 0.023-0.028" thickness range. Manufactured to ASME B18.21.1 standards for dimensional accuracy and performance reliability, the washer ensures proper fit and function in inch-system applications. The product maintains full compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, containing no restricted substances above threshold limits. The black oxide steel construction with Rockwell C40 hardness provides consistent mechanical properties and meets industrial requirements for countersunk tooth lock washers in demanding vibration environments.