The cycle life of a spring cannot be determined (only predicted) as many variables determine a spring’s cycle life; i.e. the raw material, the environment, how the spring is used, and so forth. That being said, cycle tests can be performed and Katy Spring can assist with cycle testing!
So, what is spring cycle testing?
Spring cycle testing is conducted to test a spring’s (or several springs simultaneously) fatigue life in the spring’s application or its duplicate application. The spring deflects between its working load points repetitively as the loads are checked periodically for fatigue or loss in force. Katy Spring can cycle test all types of springs including compression springs, extension springs, torsion springs, flat springs along with and including the many types of materials springs are made with; stainless, carbon steel, high-nickel alloys, brass, and phosphorous wire.
What is spring fatigue?
Fatigue is an issue where springs are subjected to cycle loading, the force of the spring varies between two load point values over a period of time. For example, the valve springs in a car’s engine can be subject to fatigue and over time, excessive cyclic stresses from fatigue can cause the spring to fatigue or even fail.
What are some ways to avoid spring fatigue?
The short answer is: a good spring design. Far too often, Katy Spring is helping customers that have created a device that needs a spring, however, there is not enough space in the device to design a spring that will have adequate load values to support the device’s stored energy demands, thereby causing fatigue or failure in the spring and eventually in the device.
Sometimes when it’s only possible to work within a limited space, a spring’s fatigue life can be improved with shot peening, raw material upgrades, or pre-setting.
Other factors that can help a fatigue problem are due to the application and can be improved. Corrosion, buckling, coil clash, and ID/OD interference are all possible problem areas that can often be improved Katy Spring & Mfg. can assist in improving a spring design.
What else should I know about spring fatigue?
A spring fatigue problem starts with the development of a microscopic crack which grows with every cycle. When the stress in the crack reaches the maximum tensile of the spring’s material, the spring will break where the micro crack started. It should be noted that material with the same chemical analysis and strength can have different fatigue.