Tensions allowed in disc spring DIN 2093
While flexing a disc spring, the superior layers of the disc are put under compression tensions, whereas the inferior layers are put under traction tensions. These tensions of traction are those that after an excessively high number of flexions can induce to the breakage. When the number of flexions is inferior to 5000 it can be considered as a static application.
The number of cycles that can be expected from a disc spring before it fails / breaks is determined by the magnitude of the change of tensions that occurs, at one determined point of the inferior surface while moving from the smaller flexion to the greater flexion.
Depending on the dimensions of the disc spring, this variation of tensions will be greater at point II or at point III, therefore the critical point will be point II or or point III.
Statistically, we can say that for a heavy disc the critical point may be the II and for a thin disc the critical point will be the point III.
The effects of the traction tensions can indeed be resisted to a certain extent by means of the preload of the spring in their use. The mini preload must be from approximately 15% to 20% of the total flexion, depending on the general level of tensions in the disc spring.
The extended norm at the time of making a calculation with this type of spring is the one of not surpassing 75% of its maximum movement with the objective of obtaining a longer life for the same one. The maximum movement being the difference between the level of the static height of the spring and the thickness of the same one or (ho = - t). -
Another aspect that we must consider in the use of the disc spring is the relaxation. This concept shows us the pressure loss which the disc spring is exposed to in function of time (Helical or Disc). This process is function of the pre-compression to which the spring is mounted, of the temperature of work and mainly of the precision with which the different processes of manufacturing were made such as: Heat treatment, Presseting, Hot-Presseting, etc. As an example we can say that for a high quality manufactured spring and working to room temperature the relaxation would have to be despicable.
Consult with our engineer, to calculate the form of optimal use of spring piling up and to guarantee a greater life of the same one.