Stacking Disc Springs in Parallel
Disc springs are assembled 'nested' inside each other, i.e. the same way up, the resultant force for such a column is the force element of a single disc spring multiplied by the number of 'nested' disc springs in the column, whilst the deflection remains the same as for that applicable to a single disc spring.
It must be realised that the individual disc springs in a column assembled in parallel perform as separate entities, thus generating considerable interface friction. For a given deflection, this interface friction will result in 3% increased force per interface, this must be taken into account when calculating the total force from parallel stacking.
E.G. A disc spring that requires a force of 5000N to deflect 1mm, when assembled of 3 disc springs in parallel, will require a force of 15900N to deflect 1mm.
It is advised that the number of disc springs in parallel should not normally exceed 3, or in extreme cases 5 springs, to minimise heat generated by friction or, in the case of static applications, to ensure a workable relationship between the loading and unloading characteristics. The hysteresis resulting from parallel stacking can be employed to advantage in those applications of a 'shock absorbing' nature, requiring a damping feature.
The life of disc springs in parallel arrangements is very dependant on adequate lubrication of the spring interfaces.