Evaluation and modeling of productivity and dynamic capability in high-speed machining centers

The current standards for machine tool performance evaluation do not consider productivity and dynamic capability at high feed rates. Therefore, industry does not have a basis for machine tool comparison. Testing was conducted with the Heidenhain KGM 181 grid encoder to record the actual path of the machine at high feed rates (up to 16 m/min). This paper shows the significance of linear vs. circular interpolation, acceleration and rate of change in acceleration (jerk) on the productivity and dynamic capability of this type of machine. Under high feed rate interpolations, the actual cycle time can differ significantly from the ideal cycle time (calculated with the traveled distance and programmed feed rate). A modeling approach with simple testing protocols is presented in order to predict the cycle time during machining with high feed rates. The proposed modeling approach provides less than 6% error in estimating cycle time.