Internal Tooth Washer

Internal tooth lock washers (DIN 6797 Form J) have inward-facing serrated teeth that grip the fastener shank and head underside, providing a mechanical lock with a smooth outer edge to prevent snagging.

Specification #

Dimension #

• All dimensions in mm, tolerance +/- 0.01 mm. Additional dimensions available on request.

Benefits #

Internal tooth lock washers address the need for vibration-resistant fastener locking in assemblies where a smooth outer profile is essential. The inward-facing teeth bite directly into the fastener shank and head underside, creating a mechanical lock that prevents rotational loosening without exposing sharp edges on the washer perimeter. This smooth outer edge eliminates snagging hazards on adjacent wiring, components, or operator contact surfaces. Internal tooth washers are particularly effective with small-head fasteners such as fillister head and cheese head screws, where the head diameter is close to the washer bore. They also maintain a cleaner visual appearance in visible assemblies, making them suitable for instrument panels, electronic enclosures, and telecommunications equipment.

Common Applications #

Internal tooth lock washers are specified where anti-vibration locking is needed alongside a smooth external profile and minimal surface marring.

• Electrical connections and terminal blocks
• Electronic enclosures with small-head screws
• Automotive interior trim and instrument panels
• Appliance assemblies
• Machinery with fillister head and cheese head screws
• Control panel wiring connections
• Telecommunications equipment
• Applications requiring a clean external appearance