The calculation of spindle dynamic compliance is usually performed taking into account only the mechanical system of the spindle and tool, while the influence of the machine tool frame is neglected. However, when performing machining operations characterized by high cutting forces – which typically arise e.g. during roughing – machine frame vibration may be induced. Under such conditions, a model of the spindle alone is not sufficient to predict the dynamic behaviour of the spindle; therefore, coupled models of the spindle and machine frame system need to be created. The paper presents two possible approaches that can be used for such tasks. The first approach consists in modelling the whole mechanical system in the Finite Element (FE) environment; the second one employs the technique of coupling modally reduced separate models of flexible bodies. The application of both approaches and their comparison is illustrated by an example of a real machine tool model. The influence of the machine tool frame on the spindle dynamic compliance is demonstrated using the machine tool coupled models.
Science Journal 