Hello, a colleague in my company told me about your website and I used it as a reference.
Now, I have a very basic question which I need anwser for. It is often said that the spring is “permanently deformed”, but I think this phenomenon is that when compressing the natural length of a spring by a few percent, the elasticity of the coil spring “decreases”. When this happens, the natural length of the spring is shortened and the ratio of compression is reduced, so the elasticity is reduced, or is the elasticity decreased without changing the natural length? In other words, is there a possibility that the output will decrease even if the natural length does not change? It may be a very basic thing, but please tell me.
Thank you for your inquiry, San-san!
Permanent deformation is when a spring is subjected to a force that exceeds the elastic limit of the spring (even once only).
However, in this case, it is the permanent deformation caused by the setting process.
In general, the elastic limit has a certain relationship with the tensile strength of the material, and it can be calculated to some extent depending on the material and the geometrical dimension as to how far the spring will deform.
However, the spring constant is basically unchanged. When the fatigue occurs, the natural length of the spring will become shorter, and eventually, it becomes useless.
* Setting: In the final step, high stress over the elastic limit of the material is applied to the direction of use on the spring that has been molded and heat treated. A type of plastic working.”
