The paper describes the problem of tool wear in machining processes. The importance of determining and analysing the demand of machining centres for electricity was emphasised and the potential relationship between tool wear and machine energy consumption was indicated. The paper presents the results of the measurements of cutting tool wear on the energy consumption of a machining centre based on the analysis of an actual technological process. The paper presents a method of obtaining and processing large amounts of data. The changes in the form of power consumption by the machine tool depending on the tool operation time and the machining cycle being implemented were shown. The researchers proposed the possibility of using the recorded data to develop an algorithm for automatic diagnosis of catastrophic tool wear. The usefulness of the collected and analysed data in the context of developing a method for determining the machine electricity demand was indicated.