Methods for balancing a self-centering chuck of a CNC machine

The aim of this paper is to obtain an optimal method for balancing a self-centering chuck of a CNC machine. To do this, two methods, known in literature as influence coefficient method and modified holobalancing method, are adapted to this specific application. A common error in the balancing process could be to consider the 3-jaw chuck as an isotropic system, due to its geometry. This paper reveals an anisotropic behavior of the system that cannot be neglected, as it has a direct influence on the estimation of the corrective masses. Therefore, the study has a twofold objective. First, select sensitive measuring points that take into account the anisotropic behavior. Secondly, evaluate which method best estimates the correction masses. In order to select a procedure, each method is verified by experiments on a chuck in different unbalance conditions. The experimental results show that the evaluation of the mass unbalance depends on the orientation of the sensors. In fact, the choice of a suitable measuring point allows to adopt a simpler balancing method and to reduce errors in the estimation of the corrective mass.