Reducing the energy needed for the machining processes used in manufacturing is a concrete step toward achieving a green transformation (GX). In this study, we investigated the use of a three-axis vertical machining center to drill and end mill a workpiece and evaluated the effects of different process designs and machining conditions on the energy efficiency. Evaluations of the energy consumption, which included the energy consumed during machining as well as that consumed for material mounting and tool changes, showed that the optimal process differed depending on the production volume. Furthermore, the evaluation results mostly agreed with the measurements. The proposed method can be implemented using numerical-control-program simulation data based on computer-aided manufacturing software. Thus, it is a practical energy-saving technology that does not require additional equipment. The proposed method is expected to contribute to the realization of sustainable production activities that promote a GX at manufacturing sites.

1. [1] T. Ogawa, “Building of efficient, energy-saving lines with an extremely-compact machining center and CNC lathe,” Int. J. Automation Technol., Vol.4, No.2, pp. 150-154, 2010. https://doi.org/10.20965/ijat.2010.p0150
2. [2] N. Uchiyama, Y. Ogawa, and S. Sano, “Energy saving for gantry-type feed drives by synchronous and contouring control,” Int. J. Automation Technol., Vol.6, No.3, pp. 363-368, 2012. https://doi.org/10.20965/ijat.2012.p0363
3. [3] K. Mori et al., “Energy efficiency improvement of machine tool spindle cooling system with on-off control,” CIRP J. of Manufacturing Science and Technology, Vol.25, pp. 14-21, 2019. https://doi.org/10.1016/j.cirpj.2019.04.003
4. [4] B. Denkena et al., “Energy efficient supply of cutting fluids in machining by utilizing flow rate control,” CIRP Annals, Vol.72, Issue 1, pp. 349-352, 2023. https://doi.org/10.1016/j.cirp.2023.04.082
5. [5] M. Fujishima, H. Shimanoe, and M. Mori, “Reducing the energy consumption of machine tools,” Int. J. Automation Technol., Vol.11, No.4, pp. 601-607, 2017. https://doi.org/10.20965/ijat.2017.p0601
6. [6] A. M. M. Ullah et al., “Strategies for developing milling tools from the viewpoint of sustainable manufacturing,” Int. J. Automation Technol., Vol.10, No.5, pp. 727-36, 2016. https://doi.org/10.20965/ijat.2016.p0727
7. [7] A. Hayashi, F. Arai, and Y. Morimoto, “Simulation of energy consumption during machine tool operations based on NC data,” Int. J. Automation Technol., Vol.15, No.6, pp. 764-773, 2021. https://doi.org/10.20965/ijat.2021.p0764
8. [8] K. Fang et al., “A new approach to scheduling in manufacturing for power consumption and carbon footprint reduction,” J. of Manufacturing Systems, Vol.30, No.4, pp. 234-240, 2011. https://doi.org/10.1016/j.jmsy.2011.08.004
9. [9] T. Samukawa and H. Suwa, “An optimization of energy-efficiency in machining manufacturing systems based on a framework of multi-mode RCPSP,” Int. J. Automation Technol., Vol.10, No.6, pp. 985-992, 2016. https://doi.org/10.20965/ijat.2016.p0985
10. [10] M. Ertem, “Renewable energy-aware machine scheduling under intermittent energy supply,” IEEE Access, Vol.12, pp. 23613-23625, 2024. https://doi.org/10.1109/ACCESS.2024.3365074
11. [11] M. K. Chinnathai and B. Alkan, “A digital life-cycle management framework for sustainable smart manufacturing in energy intensive industries,” J. of Cleaner Production, Vol.419, Article No.138259, 2023. https://doi.org/10.1016/j.jclepro.2023.138259
12. [12] B. Denkena et al., “Energy efficient machine tools,” CIRP Annals, Vol.69, Issue 2, pp. 646-667, 2020. https://doi.org/10.1016/j.cirp.2020.05.008
13. [13] T. Samukawa and H. Suwa, “Energy efficiency assessment using material removal rate and its application to wet and dry end-milling.” J. of the Japan Society for Precision Engineering, Vol.91, No.5, pp. 579-585, 2025. https://doi.org/10.2493/jjspe.91.579
14. [14] T. Matsumura et al., “Predictive cutting force model and cutting force chart for milling with cutter axis inclination,” Int. J. Automation Technol., Vol.7, No.1, pp. 30-38, 2013. 10.20965/ijat.2013.p0030
15. [15] H. Narita, “A method for using a virtual machining simulation to consider both equivalent CO₂ emissions and machining costs in determining cutting conditions,” Int. J. Automation Technol., Vol.9, No.2, pp. 115-121, 2015. https://doi.org/10.20965/ijat.2015.p0115
16. [16] L. Hu et al., “Minimising the machining energy consumption of a machine tool by sequencing the features of a part,” Energy, Vol.121, pp. 292-305, 2017. https://doi.org/10.1016/j.energy.2017.01.039
17. [17] Y. Oda, M. Fujishima, and Y. Takeuchi, “Energy-saving machining of multi-functional machine tools,” Int. J. Automation Technol., Vol.9, No.2, pp. 135-142, 2015. https://doi.org/10.20965/ijat.2015.p0135
18. [18] A. Fysikopoulos et al., “On a generalized approach to manufacturing energy efficiency,” Int. J. of Advanced Manufacturing Technology, Vol.73, pp. 1437-1452, 2014. https://doi.org/10.1007/s00170-014-5818-3
19. [19] T. Gutowski, J. Dahmu,s and A. Thiriez, “Electrical energy requirements for manufacturing processes,” Proc. of 13th CIRP Int. Conf. on Life Cycle Engineering, 2006.
20. [20] S. Kara and W. Li, “Unit process energy consumption models for material removal processes,” CIRP Annals, Vol.60, pp. 37-40, 2011. https://doi.org/10.1016/j.cirp.2011.03.018
21. [21] Y. Guo et al., “Optimization of energy consumption and surface quality in finish turning,” Procedia CIRP, Vol.1, pp. 512-517, 2012. https://doi.org/10.1016/j.procir.2012.04.091
22. [22] L. Li, J. Yan, and Z. Xing, “Energy requirements evaluation of milling machines based on thermal equilibrium and empirical modelling,” J. of Cleaner Production, Vol.52, pp. 113-121, 2013. https://doi.org/10.1016/j.jclepro.2013.02.039
23. [23] S. Velchev et al., “Empirical models for specific energy consumption and optimization of cutting parameters for minimizing energy consumption during turning,” J. of Cleaner Production, Vol.80, pp. 139-149, 2014. https://doi.org/10.1016/j.jclepro.2014.05.099
24. [24] M. P. Sealy et al., “Energy consumption and modeling in precision hard milling,” J. of Cleaner Production, Vol.135, pp. 1591-1601, 2016. https://doi.org/10.1016/j.jclepro.2015.10.094
25. [25] T. Samukawa and H. Suwa, “A basic study of predicting in-process energy consumption in machining based on specific energy consumption,” J. of the Japan Society for Precision Engineering, Vol.83 No.4, pp. 367-374, 2017 (in Japanese). https://doi.org/10.2493/jjspe.83.367
26. [26] T. Samukawa, K. Shimomoto, and H. Suwa, “Estimation of in-process power consumption in face milling by specific energy consumption models,” Int. J. Automation Technol., Vol.14 No.6, pp. 951-958, 2020. https://doi.org/10.20965/ijat.2020.p0951
27. [27] K. Shimomoto, Y. Otomura, and T. Samukawa, “Effect of drilling conditions on CO₂ emissions,” J. of the Japanese Society for Experimental Mechanics, Vol.23, No.1, pp. 45-50, 2023 (in Japanese). https://doi.org/10.11395/jjsem.23.45