Heat treatment is of major importance for properties of a spring. Therefore, we heat treat all springs of ordinary spring steel – as long as they are not manufactured of spring-hard material – using an isothermal annealing. This enables a so-called bainite stage to ensure that the springs attain the highest strength, and at the same time a high degree of toughness and optimal fatigue resistance.

According to DIN 2093 the hardness of disc springs should be 42 – 52 HRC. With our springs, hardness is related inversely to disc thickness.