Compression springs are used in many industries and types of business to absorb, store, and return mechanical forces. Choosing the best available spring for a given application will always make a successful project more likely.
Leading compression spring manufacturers work tirelessly to make sure customers are well-informed about their products. In most cases, the various springs that seem nominally suitable for a given use will still vary in some significant ways.
Focusing on the most important issues will make it easier to choose a compression spring that will perform well in practice. The four factors that follow tend to make the most difference in real-world situations.
- Spring Rate
Some helical springs are designed to resist and buffer forces that pull outward along the winding axis. Compression springs do the opposite, starting from a resting position that includes empty space between adjacent coils.
How much force it takes to compress a spring a set distance will always depend upon a number of factors. In many common situations, this figure ends up being the most important feature of a given spring.
Spring rate is most often expressed in terms of Newtons per meter or pounds of force per inch of deflection. Larger numbers indicate stiffer springs that deflect less when a set amount of force is applied.
Most applications for compression springs will include relatively well-defined forces and spaces, which should normally make identifying a range of suitable spring rates straightforward. In cases where such requirements have not yet been pinned down, taking some measurements will make for a good start.
- Stress Resistance
Like other moving mechanical parts, compression springs eventually succumb to the wear caused by stress. Instead of simply breaking down, springs that have been subjected to too much force over time become “set” in a partially compressed state whose magnitude corresponds to the amount of strain that has accumulated.
Manufacturers typically estimate how many duty cycles their springs can endure before giving in to stress. Figuring out how long a spring will need to retain its original characteristics will make it easier to determine how much stress resistance will be required for a given project.
- Expanded Diameter
When a compression spring deflects any distance in response to a force, its coils also expand to some extent or another. This bulging will not always be regular, with some springs exhibiting more expansion toward the middle or the ends.
In some cases, a spring’s diameter when it has compressed as much as possible will not be important. In many others, housings or adjacent parts will limit the amount of expansion that can be accommodated. Once again, being clear about the requirements inherent in a given project will make it easier to choose an appropriate spring.
- End Type
Although they are not always relevant to the primary function of a compression spring, the ways by which ends can be finished often matter in practice. The coils at the ends of compression springs can either be left open or closed, the latter of which will add to the cost of manufacturing.
Terminal coils can also be ground flat or left rounded. There are four possible ways to finish compression spring ends, all of which are commonly used on actual products. Springs with closed, ground ends tend to be chosen when stability and regularity matter the most. Open ends that are not ground are typically found on inexpensive products.
Although there are other ways that some compression springs differ from others, the four issues above tend to be the most significant. Focusing on these factors should normally make it fairly simple to identify one or more types of springs that will suit a targeted application.