Compression Springs
Coil springs called compression springs can store mechanical energy when they are compressed. These open-coiled, helical springs provide resistance to compressive loading. When these springs are subjected to a compression load, they compress, grow shorter, and absorb a large amount of potential force.
The springs are forced back to their original lengths and forms after the load is reduced or eliminated by the stored energy. When weighted, compression springs become more compact. In contrast to extension springs, compression springs' spiral wires do not contact when they are relaxed; instead, when stressed, they are tightly compressed.
There are various considerations when choosing compression springs which include:
I. Compression Spring End Types
Compression spring end types might be normal or customized. Standard ends can be open or closed, or they can be ground or not. Given the same number of coils, wire size, and outside diameter (OD), open or closed ends will alter the spring rate.
1. Closed Ends
Closed ends stand vertically when placed on a flat surface since the last coil is closed. They are the most popular and economical ends since they do not require any form of extra processing. With applications that have a slenderness ratio, closed end compression springs will require a shaft or rod for extra support.
2. Ground Ends
Ground end compression springs are closed end compression springs that have their ends ground to the size of the spring. The grinding process increases manufacturing time and the cost of each spring. Grinding of ground end compression springs gives them a slenderness ratio to be able to function without the need of a rod or shaft.
3. Double Closed Ends
Double closed ends are similar to closed and squared ends. Instead of having one closed end, double closed end compression springs have two.. They are manufactured like extension and torsion springs with all coils touching. Double closed end compression springs have extra stability with a high slenderness ratio that requires a reinforced end in order to prevent buckling. They can be more economical than closed or ground end compression springs.
4. Open End
Open end compression springs are the least common type of compression springs because the open end does not allow the spring to stand or be stable without the assistance of a rod or shaft to keep the spring in place. AIl the coils are open and have pitch between them. Open end compression springs are used in applications where it is necessary to avoid increasing the solid height of the spring.
II. Compression Spring Physical Considerations
1. Outer Diameter (OD): If the compression spring is going into a hole, its outside diameter should be considered. In any case, if any internal components of the device will surround the spring, those must also be measured. A spring's outer diameter (OD) will enlarge when it is compressed, which is also important to consider if the spring will be used in a tube or a bore. Outer Diameter is measured from the outside of the coil on one side to the outside coil on the opposite side.
The outside diameter of springs is also subject to manufacturing limitations, which can increase the assembly's needed envelope size. Most spring manufacturers will specify a work-in-hole diameter for a spring based on projected OD expansion and manufacturing tolerance. Use this information to more effectively express the product needs when obtaining custom-made springs or to easily choose from stock spring catalogs.
2. Inner Diameter (ID): If the compression spring passes over a shaft or mandrel, the spring's inner diameter needs to be considered. To prevent friction, there must be a ten-thousandth of an inch between the shaft and the spring. Inner Diameter is calculated by subtracting two wire diameters from the outer diameter.
3. Free Length: To ensure that the compression spring is in a preloaded state and stays in position, it is advised that its free length be a little bit longer than the available space. Free Length is the length of a compression spring before it is compressed, loaded or experiences any force. It is the length of the spring from end to end or tip to tip.
4. Solid Height: The wire diameter and the total number of coils impact the solid height of the spring. Make sure the loaded height is not shorter or taller than the solid height.
The setting in which the spring will be used includes the temperature and additional components such as moisture. The more expensive the spring's material, the higher the temperature a spring can withstand, but this will increase its cost.
5. Spring Pitch: Spring pitch is the distance between adjacent coils from the center of one wire to the center of another wire. The simplest method for measuring pitch is to measure the gap between the coils and add the thickness of a wire.
6. Active Coils: With compression springs, active coils are the coils that have pitch that deflect when the load is placed on the spring.
7. Total Coils: Total coils of a compression spring are all of the coils including the closed coils without pitch. The use of compression springs requires an understanding of the number of total and active coils. Ones with closed and square ends or ground ends have one closed coil at each end, which are inactive. With open end compression springs, all of the coils in the spring are active and carry the load.
III. Different Types of Compression Springs
1. Convex Compression Springs
2. Conical Compression Springs
3. Disc Springs or Belleville Springs
4. Concave Springs
5. Straight Coil Compression Springs
6. Volute Springs
7. Variable Pitch Spring
8. Magazine Springs
The majority of the information above is excerpted from IQSDirectory.com.
