Metric Washer Dimensions
WHAT IS THE REAL PURPOSE OF WASHERS AND WHY ARE THEY USED?
The primary purpose of washers is to reduce the risk of damage and distribute the load of the threaded fastener with which they are used.
Threaded fasteners stress the material that they are driven into. For example, driving a screw into a wooden surface may crack the surface and damage the internal grain structure.
Not all materials require washers, but for wood and other softer materials, it is generally safer to incorporate washers to spread the load over a larger area.
Washers can also be used as spacers, but why?
It is not possible to drive a threaded fastener if it is longer than the depth of the object, which will leave part of the fastener protruding out the back of the object and possibly damage it.
The correct placement of a washer can easily combat this as it creates padding so that the fastener does not go too deep.
Certain types of washers are designed to absorb vibrations, also known as vibration damping or vibration-isolating washers.
Typically, they are made from a soft material such as plastic, rubber, or urethane, rather than metal.
Softer materials are better equipped to handle vibrations when compared to hard materials like metal.
A vibration damping washer can protect objects that vibrate aggressively, such as within planes or cars.
Sometimes a combination of washers can be used, such as a rubber washer under a flat washer, this gives vibration isolation and load spreading.
Liquid-sealing washers can be used to create a waterproof seal to prevent seepage water or other liquids. The washer is made from soft materials such as neoprene rubber, this provides better leak protection when pressed completely against the surface of the object.
PREVENTING GALVANIC CORROSION
Washers can be used to help prevent galvanic corrosion, especially when using steel screws on aluminium surfaces. (see the anodic index page for details).
WHEN SHOULD YOU USE WASHERS WITH BOLTS?
Bolts are more reliable when used with washers. They protect the surface from damage during installation by distributing the pressure to give the nut a smooth, even surface to tighten against, which helps to prevent corrosion and pull-through, especially with softer materials.
Skipping washers can dramatically reduce the lifespan of your product or wherever it is being applied.
The charts below gives the dimensions for Metric flat, spring, internal tooth, external tooth and Nordlock washers.
Dimensions shown are in mm, if you wish to convert to Inches, please use our universal converter.
We also have information on Imperial Washers