Tool wear monitoring by using the imaginary part of the transfer function of the cutting dynamics

A new index for tool wear monitoring, the imaginary part of the inner modulation transfer function of the cutting process, is introduced. As a methodology to identify and isolate the factors related to wear from other effects, the time-series method is utilized to formulate a general model for the three-dimensional cutting dynamics. This model is first reduced to a multi-input single-output model and subsequently to a single-input single-output model, which is implemented fof on-line tool wear monitoring. A newly developed dual computer system in which one computer performs measurements while the other estimates the parameters by the batch least squares methods is developed and used for the verification of the feasibility of the proposed concept.