Defining Solid Height and its Role in Compression Springs, Part 1

There are several terms within the spring engineering world that are very important for helping define the qualities of a given spring and its uses. Many of these terms relate to the level of compression within a given compression spring, including a well-known spring term known as “solid height.”

At Custom Spring Manufacturing, compression springs are just one of many custom springs we manufacture for our clients as needed, a list that also includes everything from conical springs and flowline springs to torsion springs and many others. In this two-part blog, we’ll go over everything you need to know about solid height for your compression springs, from its simple definition and how its calculated to the role it plays in defining ideal applications and other important metrics within the spring world.

solid height compression springs

Solid Height Definition

As many who have worked with them are well aware, compression springs are generally designed to resist force through their ability to compress when weight is applied. They have a certain number of coils, meaning that at a certain pressure point, the coils will begin overlapping and touching each other.

When all the coils in a given spring are touching each other and cannot deflect any further from a compression standpoint, this is the solid height of the spring. While more force can often be put on the spring, depending on the metal quality and other factors, such force will not cause the height of the compressed springs to change in any way.

Calculation Method for Solid Height

Now, you might think that calculating solid height would be relatively straightforward, and you’d be close – but not exactly right. Let’s assume a basic compression spring with 10 coils, one made from 0.28-inch wire; you’d think the calculation for solid height would just be 10 X 0.28, right?

Close. In reality, you actually have 11 sides of wire for those 10 coils – the 10th coil touches the adjacent coil on the end, creating this 11th side. So instead of multiplying the wire width by the exact number of coils, you multiply it by that number plus one. The only exception here will be for closed and ground ends, in which case you should just use the total number of coils for your multiplication.

Our subsequent sections will go over some situations where solid height plays a major role in a given application or selection of a compression spring.

Solid Height and Precision

In many cases, a spring designer will desire a spring that reaches solid height at a precise moment. One example here is the spring found at the bottom of various liquid bottle-filling machines – the designer of this spring will want it to reach solid height at the precise moment when the proper amount of liquid is present in the mechanism, which signals to the machine that it’s time to shut off and move the bottle to the next station.

For more on compression spring solid height, or to learn about any of our custom spring services, speak to the staff at Custom Spring Manufacturing today.