Lockwashers offer an easy and effective way to protect fasteners from vibration-related loosening. Over time, vibrations can cause nuts and bolts to loosen. Lock washers, however, feature teeth that grip to prevent loosening. As you tighten the bolt or nut, the teeth will dig in to create tension. There are different styles of lockwashers, however, such as internal tooth and external tooth.
What Are Internal Tooth Lockwashers?
Internal tooth lockwashers are characterized by inward-facing teeth. They have serrated notches or “teeth” on the inside edge. These internal teeth grip under the head of a bolt.
All bolts have a head. It’s the uppermost part of a bolt that features the drive recess or drive type. Phillips head bolts have a Phillips head drive recess, whereas slotted bolts have a slotted or flat-head drive recess. Regardless, internal tooth lockwashers are designed to grip under the head of a bolt to prevent it from loosening.
What Are External Tooth Lockwashers?
External tooth lockwashers are characterized by outward-facing teeth. They feature teeth on the outer edge. These external teeth extend beyond the ring of the washer to provide a strong hold.
Differences Between Internal and External Lockwashers
Internal and external lockwashers share many similarities. They both have teeth to protect fasteners from vibration-related loosening, and they are both available in a variety of materials and sizes. The main difference lies in the orientation of their teeth.
Internal lockwashers have inward-facing teeth, whereas external lockwashers have outward-facing teeth. The photo at the top of this post depicts external tooth lockwashers. The teeth are positioned on the outer edge and point outward, so the depicted lockwashers are external lockwashers. Internal lockwashers have teeth as well, but their teeth are located on the inside edge and point inward.
While they both protect against vibration-related loosening, external tooth lockwashers offer a stronger hold than their internal tooth counterparts. With their outward-facing teeth, they are able to create a more aggressive hold. For high-torque applications, you may want to choose external tooth lockwashers for this reason.
Internal tooth lockwashers, on the other hand, offer a cleaner appearance. The teeth are not visible outside, making them look neater and more streamlined.
In Conclusion
Choosing between internal and external tooth lockwashers depends on your specific application needs. Internal tooth lockwashers are great for lighter-duty jobs and softer materials, while external tooth lockwashers offer more grip for tougher applications.