The service life refers to the number of extractions and retractions that a spring can perform within the working range without breakage.
Constant force springs are most commonly used in applications which, depending on the installation space and the required
spring forces, subject the spring steel strip to high bending stresses.
The service life of the spring is then defined in the lower range of the fatigue strength in the order of 5,000 to 20,000 load cycles.
If higher requirements need to be met, the effort that goes into design and the installation space must be significantly increased.