People use lock washers to avoid nuts and bolts turning […]
People use lock washers to avoid nuts and bolts turning, slipping and coming loose because of vibration and torque. Different din975 washers perform this function in slightly different ways, but the basic concept is to hold the nut and bolt in place. Some lock washers achieve this function by biting into the base material (bolt) and the nut with their ends.
Lock washers provide resistance against vibration. When you choose the suitable lock washers for your job, you should consider three parameters - inside diameter, outside diameter and minimum thickness range.
Helical or split lock washers look like a ring with uneven ends. The ends of the ring bite into fastener material to keep it from turning. Internal-tooth lock washers have teeth located on the inside of the ring and provide a good connection with small fastener heads. External-tooth lock washer have the teeth located on the outside of the washer ring, which works well with large fastener heads. External-Internal/Combination lock washers have teeth on both the inside and outside of the ring. This provides better security with large fastener heads. Pyramidal-type lock washers are used for projects requiring high-tightening torques. Countersunk lock washers are used with flat or oval head screws having either 82 or 100-degree countersunk angles. Dome-type lock washers distribute load over a wide area and are recommended for use with thin or soft materials that require high torque for holding. Dish lock washers are similar to domed lock washers but can be used in applications requiring less torque or load.
If it need to use a nut-and-bolt configuration, you’d better place the lock washer between the nut and the work surface or between the fastener head and the work surface. In other words, the bolt goes straight into the hole and doesn't poke out the other end, so no nut is used.
Verify that the teeth of the locking washer engage completely with both the fastener -- or nut -- head and the work surface. If the teeth on the washer don’t engage with both surfaces, it won’t hold. Change sizes or styles of lock washer as needed to ensure the washer’s teeth mate with the work surface and fastener head before proceeding. If you’re using a split washer, skip this step.
Tighten the nut or bolt to the torque specified in your project manual. You should use a torque wrench in order to make sure that the suitable torque is achieved.
Inspect the locking washer to, once again, verify that the teeth are completely hidden by the fastener head and the work surface. If you’re using a split -- also known as helical -- washer, inspect the washer to confirm that it is still “split,” with one side out of alignment with the other so that the washer exerts spring tension on the fastener. If the required torque flattens the split washer into the shape of a standard washer, it will no longer function as a locking washer; use a toothed locking washer instead.