Innovative CNC Technology for Sustainable and Highly Efficient Manufacturing

Analyses of metal-cutting processes have shown that the auxiliary components in the machine tool or its environment play a dominant role in the energy balance [1]. The power consumption of a CNC control including infeed and spindle motors usually comprises only 25 to 30% of the total input power required to operate the machine [1]. Most of the electrical energy is required to supply the auxiliary components for processing cooling lubricants, for supplying compressed air and hydraulics and for cooling of feed and spindle motors [2] [3]. A study on the energy consumption of machine tools has underlined that machines consume in standby more than 50% of the energy that is required in cutting operation [1]. In general, the efficiency of CNC power electronics is very high [2]. Based on the latest generation of power semiconductors and new control algorithm, HEIDENHAIN’s generation 3 power electronics has even improved the energy balance of the control cabinet. However, a major step on the road map of carbon footprint reduction based on further efficiency improvements of the CNC electronics seems to be unrealistic. In contrast, a proper management of pumps, cooling aggregates and a reduction of the compressed air consumption promise significant energy savings [2] [3]. Consequently, HEIDENHAIN’s new linear absolute position feedback systems for machine tools will no longer require compressed air during operation. A new innovative scanning technology and a new sealing concept allow proper and reliable operation without the need of compressed air. Figure 1 shows the average input power of three different machine types which are specified in table 1, [1]. The results point out, that a high level of automation for 24/7 operation of machine tools has significant impact on the energy consumption. As parts and fixtures need to be cleaned to 100% to avoid clamping errors caused by remaining chips in the machine workspace, the energy consumption to process the cooling liquid increases significantly [1] [3]. However, automation allows significant higher throughput, and the energy consumption per part might decrease in comparison with non-automated machines.