Nuts and bolts are common household fasteners that have a multitude of uses. While they may be effect by themselves, oftentimes the addition of a washer to one or both sides can increase their strength, appearance and efficiency. Different types of washers provide different advantages. Before reaching for a flat washer or a lock washer, it is important to know what you wish to accomplish.
Flat washers are used to increase the surface area in order to more evenly distribute the force applied with tightening the fastener. Lock washers are used as a means of creating tension during tightening in order to help keep the nut from working loose later.
There are a number of types of both flat and lock washers. Flat washers come in common flat, United States Standard (USS) flat, Society of Automotive Engineers (SAE) flat, fender flat, dock flat and other styles. Lock washers come in common lock, high collar lock, external tooth lock, internal tooth lock and others.
Both flat and lock washers come in a wide variety of interior diameters, exterior diameters and thicknesses. Flat washers may be constructed from a variety of materials including brass, silicon bronze, stainless steel, zinc plated steel, chrome, rubber and many others. Lock washers may also be made from a number of different materials including stainless steel, zinc plated steel, silicon bronze, galvanised steel and many others.
Flat and lock washers may be used for a number of different applications depending on their size and composition. Silicon bronze washers are frequently used for marine projects, such as wood boat restorations, due to their strength and superior corrosion resistance. Zinc plated and galvanised steel washers can provide good protection against rust. Stainless steel is used for most common applications and chrome washers, with their high gloss finish, are used primarily in areas where they are intended to be seen.
Flat washers may be used on either the bolt side, the nut side or both sides of the fastener. Flat washers help to distribute the force of tightening the nut by increasing the surface area. They may also be useful as spacers when a bolt may be a bit too long for the job. Lock washers are typically used on the nut side of the fastener. The most common type of lock washer is the split coil washer. This type of washer creates tension as the coil is forced down by the tightening of the nut. This tension helps to keep the nut in place. Lock washers are frequently used in applications that involve vibration which may tend to work the nut loose.