Modeling and characterization of an electromagnetic system for the estimation of Frequency Response Function of spindle

•A specific device to measure the dynamic behavior of high speed spindles is presented.•The applied force is estimated from the control current.•The relative permeability of the magnetic core is updated from a specific experiment.•The performance of the system is validated on industrial spindle, at up to 5 kHz. The paper presents an electromagnetic system that has been developed to measure the quasi-static and dynamic behavior of machine-tool spindle, at different spindle speeds. This system consists in four Pulse Width Modulation amplifiers and four electromagnets to produce magnetic forces of ±190 N for the static mode and ±80 N for the dynamic mode up to 5 kHz. In order to measure the Frequency Response Function (FRF) of spindle, the applied force is required, which is a key issue. A dynamic force model is proposed in order to obtain the load from the measured current in the amplifiers. The model depends on the exciting frequency and on the magnetic characteristics of the system. The predicted force at high speed is validated with a specific experiment and the performance limits of the experimental device are investigated. The FRF obtained with the electromagnetic system is compared to a classical tap test measurement.