Modeling of the holding force in an electromagnetic chuck

Addresses the modeling and prediction of the holding force in an electromagnetic chuck used in precision machining. First, an analytic model termed the magnetic circuit model was developed and compared with experimental holding force data. It was found that this model, although simple in form, was limited in its range of application. The discrepancies in the model were attributed to its inability to accurately represent the leakage flux and the non-uniform distribution of the magnetic flux. A three-dimensional finite element model was then developed to overcome these limitations. Predictions with this model were found to be in better agreement with the experiments, yielding prediction errors within 25% for most cases. The finite element model also provides an explanation for the decrease observed in the measured holding force past its maximum value.