Performance of an automatic ball balancer with dry friction

In many industrial applications imbalance is a major cause for unwanted vibrations. One way to compensate for an unknown imbalance is the implementation of an automatic ball balancer. Oil-lubricated automatic ball balancers are applied in hand-held tools and washers. However, in applications such as optical drives fluid lubrication is highly undesirable since it may destroy the optical system upon leakage. Therefore, in this paper, the balancing performance of an automatic ball balancer without fluid lubrication is investigated. The absence of fluid lubrication gives rise to dry friction phenomena which cause the existence of equilibrium sets of the balls in the automatic ball balancer. A model of the system with dry friction, modeled by a set-valued force law, is built based on dedicated experiments. The resulting equilibrium sets and their dependency on system parameters are studied and the consequences for the balancing performance is assessed. Based on these results, it can be concluded that in parts of such equilibrium sets the balancing performance deteriorates when compared to the system without automatic ball balancer; in other words, the balancing performance is endangered by the presence of dry friction. This conclusion is supported by both numerical and experimental results.