You must have often seen a disk-shaped thin plate having a hole in the center used in your nut and bolt assembly and wondering why this part is used.

This is a washer and it plays a significant role in keeping your mechanical assembly intact.

316SS AN 900 washers4

AN-900 series washers

There are 316SS AN 900 washers available on the market has got a smaller outer diameter with a specified thickness. The name “AN” has come because they meet the military specifications of the US for the Air Force and Navy application.

Why a washer is important?

A famous fire incident where a Boeing 737 caught fire while landing in Japan just because someone forgot to use a washer where it was meant for.

So, you can understand that this humble-looking washer has many purposes. Some of them are:

  • Protects any bolt or screws from cracking
  • Protects fasteners against corrosion if mating parts are different
  • Keeps the nut bolt assembly tight
  • Locks the mechanical assembly against vibration

What are the different types of washers?


Flat washers

This thin, circular, and flat surface with a hole is a simple washer meant for dispersing the load from the bolt/screw and nut across a large region.


Consider utilizing C-washers if the washer must be taken out or replaced often. Simply losing the screw will allow us to slip this in and out with ease.

Shoulder washers

Also, called an insulating sleeve. When you need to remove screws from its mating surface for different reasons, such as heat flow, electrical insulation, etc., think about the shoulder washer.

Clipped washer

They are meant for preventing the washer from getting turned and loose by assembling this washer with a certain flat edge on the outside surface for aligning with a flat surface.

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Countersunk washers

Countersunk washers must be used with certain countersunk screws. This washer can keep the screw head in flush condition without the countersunk hole. Used if you require a flush surface without any screw head protruding out.


Fender washers

Similar to the above flat washer but having a large outside diameter with a regular inside diameter. Mostly used in thin metal components. The main applications are in automobiles, paneling, and plumbing.

Torque washers

A torque washer can be ideal for use in various woodworking projects where bolts are required not to move around. However, it is more effective in soft materials only.

Lock washers

Lock washers are meant to secure fasteners against any loosening due to rotation or any loss of friction. Several types of lock washers are available in the market. All work under a similar principle.


Spring washers

This simple and brilliant washer design can be used in conditions where you need to compensate for any movement in assembly, and it will act as a shock absorber.

Belleville washers

More of a spring than a washer, this. Belleville washers are spring-like and can support a greater load with little deflection. By stacking during assembly, you can increase its capacity for load carrying.

Wave washers

The wave-like design of wave washers allows for a modest load capacity and deflection. They frequently serve as cushions or dividers.

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