Tool wear monitoring based on a non-monotonic signal feature

Most tool-condition-monitoring (TCM) strategies are founded on the assumption that the monitored diagnostic signal feature is increasing, the monotonic function of the tool wear, but this is not always the case. The paper presents the TCM strategy based on non-monotonic signal features. The used-up portion of the tool life (Delta T=t/T) was used as the tool condition indicator. It is much more informative than the direct value of a sensor signal or any signal feature, and more practical than tool wear measures (VB and KT) which are not usually measured in factory floor conditions.