Why do other Belleville manufacturers have different flat loads listed for the same size spring?
Almost all Belleville spring manufacturers employ a calculation derived by Almen and Lazlo. This derivation makes several assumptions such as sharp corners and that the parts are loaded at the corners. However, in most bolting applications, the springs are loaded between a flat surface (the joint) and a nut (or bolt head). As the spring is loaded close to its flat position, it begins to ‘bottom out.’ In other words, the contact points are no longer at the corners. As a result, load increases non-linearly as the flat load is approached. The loads listed in Solon’s catalog take this phenomenon into account.
