1. Belleville is a disk spring
Belleville is a disk spring that applies pressure to the connection once you clamp down on it with
the proper amount of force. The advantage of this washer is that it applies clamping pressure
along a continuous arc pattern, instead of concentrating it at one point the way a split-ring lock
washer does.
A Belleville Washer is a cupped spring washer or conical washer, with a slight conical shape. It
provides an axial force when deformed. This conical configuration enables the Belleville Washer
to support high loads with relatively small deflections and solid heights, compared to helical
springs.
Belleville Washers are often used to solve vibration, thermal expansion and relaxation and bolt
creep problems.
Manufactured from 300 Series Stainless Steel, Lee Spring Belleville Washers offer good
corrosion resistance for most applications. Additionally, Lee Spring Washers are passivated in
accordance with specification ASTM A967 (supercedes QQ-P-35) to remove contaminants and
further improve resistance to corrosion. 300 Series Stainless Steel is slightly magnetic and is
recommended for any applications where the temperature is below 500° F (260° C).
Belleville Washer stacking
By stacking Belleville Washers in various configurations, additional load flexibility can be
achieved. Belleville Washers can be used in four different ways:
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Single: One washer
Parallel: All washers stacked the same way
Series: All washers stacked opposite each other
Series-Parallel: A combination of the two
While you should use a split-ring washer only at the nut end of the connection (normally), you
can use Belleville washers in tandem. One at the nut end and one at the bolt head end. This is a
common way to use these washers, especially when assembling bus bar.
Most often, you’ll find Belleville washers in applications where you have to connect bare, soft
aluminum to aluminum or copper, or where you have conditions of high current loading or
cycling. These washers do wonders for accommodating thermal cycling, but they can’t eliminate
all the problems resulting from poor workmanship. You must prepare the joint properly (as with
any connection), but the key is selecting the proper design and size of Belleville washer for the
fasteners and conditions of your application.
Selecting the right Belleville washer You have to deal with three parameters here: torque,
diameter, and finish. Vendors publish the specification data you need in various media, such as

2. booklets, CD-ROMs, and websites. These are high-end fasteners for electrical applications, so
your source would most likely be your electrical supply house you normally deal with. Let’s look
at these three parameters.
Torque. This is the force you need to place on the bolt to flatten the washer to its optimum shape
for proper clamping. Remember, the way a bolt makes a tight connection is by your tightening it
to the point where its threads just start to deform. Bolts of various hardness, diameter, and
material configurations require varying amounts of torque to reach that tightness. This is the
same with Belleville washers. So that the bolt and Belleville washers work together, make sure
the torque for your Belleville washers matches that of your bolts.
If you exceed a locking washer’s torque by more than a few percent during assembly, you
destroy the locking washer. Again, Belleville washers are no exception. If you undertorque, you
won’t make use of the washer’s abilities to provide a reliable connection.
Diameter. A Belleville washer generates a clamping force along the tip of its cup perimeter. If
the cup overhangs the connection (e.g., it’s too big), you’ll have much less clamping force than
you thought you had.