Lock washers work by applying a spring force against the nut or bolt head. Different lock 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 bolt and the nut with their ends which resists turning and slipping caused by vibration and torque.
Most lock washers work on one of two principles: compression and an interlock or a bite. Either way, using the correct lock washer the correct way is important in keeping nuts and hardware from loosening and possibly causing damage. Lock washers come in different types. Each is designed for use in a particular application. Some lock washers look like rings with uneven ends, and others appear star shaped with an outer ring of teeth. Generally, they are made of aluminum, stainless steel, bronze, zinc, phosphor bronze alloy or carbon steel. The material used in manufacturing the lock washer is important in preventing it from breaking down, thereby losing its fastening strength. Lock washers are commonly used in applications involving vibration and possible slippage of fasteners. Industries that commonly use lock washers are transportation related (automotive, aircraft and marine), but they are also used in household appliances such as air handlers, air conditioners and washing machines.