Belleville Spring and Other Special Spring Washers
A belleville spring is just one of many designs and styles of spring washers in common use. The main types of washers in use could be grouped as either belleville, wave, slotted or finger, and curved washer.
I could not begin to list all the variations in these categories. The general shape and design style should be selected to meet the application.
The calculations for the design of these washers are as varied as their different styles. It would be difficult to cover every area so I will just try to give a good picture of the basics.
Wave washers are one of many types of flat springs used in industry. The trend toward smaller more compact machines and mechanisms made these very popular. These work well when a static load or a small working range is required of a spring and the axial space to work in is small. A wire spring would never work in this case.
This formula can be used to help calculate load/deflection and stress data. Where:
- P = load, lb.
- f = deflection, in.
- E = modulus of elasticity, psi
- t = thickness, in.
- N = number of waves
- OD= outside diameter
- ID= inside diameter
- S = stress, psi
- D = mean diameter
These formulas apply to deflections between 20% and 80% of the height available.
Remember, the diameter of a wave washer increases as the spring deflects. The new diameter, D�Œw can be calculated from the formula above.
Curved washers are great when you need a lot of flexibility and many cycles up and down through a range of motion. These are not heavy duty springs. They exert a relatively light thrust load. This spring really is useful in parts where axial end play needs to be eliminated.
You need to allow for expansion space when these washers are compressed. Beware, the edges tend to dig into the surface they are on. Make sure this surface is hard.
The best you can do is approximate the design using these formulas. The best approach is to specify the load needed and at what height. Also, determine the OD and ID for the space you want the part to work in. Then leave the final part to be determined by the spring maker.
One last note on curved washers: if used near its solid height it will have a much higher rate than calculated.
Remember, as I said before, the design formulas shown here are approximate. K is given in the chart and f is assumed to be less than 80% of h.
Slotted and finger washers are really a combination of two products. They have the flexibility of belleville springs but individual points of loading like flat springs.
These parts are great for those narrow work spaces that have a large ID and small OD. For example, they are often used in clutch assemblies or for applying axial load to ball bearings.
By combining the effects of Belleville and flat springs you get increased load deflection values. When creating the design you need to use the combination of these two spring types. This can really get quite complex. Therefore, spring manufacturers need to create and test samples to get to your final design.
There is such a wealth of information on belleville springs. Please, go to this great web page that discusses their uses and designs-
Belleville Spring Washers.
This page gets into the details and then takes you to this great page on
Belleville Spring Design Techniques
that has both a logic diagram and design example.
For information on choices of material for washers this page on
the types of spring steel used in spring making
will give you a good overview. It has links to some very useful charts.
Check back for updated information related to Belleville Spring and Other Special Spring Washers. Our team is constantly searching for items that will benefit you.
Got some info you want to share? Send it our way by going to our
Don't miss any updated information! Stay in touch by subscribing to Spring Makers Resource e-zine
Return from Belleville Spring and Other Special Spring Washers to Spring-Makers-Resource