Impact of feed axis on electrical energy demand in mechanical machining processes Isuamfon F. Edem*, Paul T. Mativenga School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL, United Kingdom *, +447404875267 Abstract To reduce energy demand in manufacturing, it is important to make products using the most energy efficient process plan and resources. In machining, understanding the factors that influence the electrical energy demand for CNC toolpaths is vital in order to determine the optimum machining conditions to minimise energy demand. In this study, a new model for estimating the electrical energy demand of machine tool feed axes which incorporates the weights of feed axes and weights of the materials placed on the machine table is presented. This was achieved by studying the electrical energy demand for machine tools when air cutting in defined axis directions, carrying a range of masses, and in actual cutting, while the electrical current was measured. The newly proposed model was validated on milling CNC toolpaths. The information enabled the development of suggestions for reducing energy demand. The energy reduction hypothesis developed was explored and validated by machining components in defined orientations on the machine table. The results are important for manufacturers in industry when process planning. The information is also valuable for the range of machine tool design and manufacturing companies in the development of energy efficient machine tools. Keywords: Energy efficiency, electrical energy demand, feed axes, machining, modelling, CNC toolpaths 1. Introduction Electrical energy demand modelling and reduction in manufacturing is important because of energy costs and the carbon footprint associated with energy generation. The electrical energy consumed by machine tools throughout their use phase results in increased environmental impact. For example, ) conducted life cycle analysis of two milling machines and reported that 60% to 90% of CO2 equivalent emissions result from the use phase of milling machines. ),
axes from the Fluke 434 power quality analyser gave 3180 W, 3385 W, and 3237 W for the aforementioned angles respectively. Thus, the deviation between the model and the measured power demand of the feed axes for the specified angles were between 1% and 2%. Also presented in Figures 13 a, b, and c are power profiles for air cutting, as well as the predicted (model) and measured power demand for the feed axes of the Takisawa Mac-V3 milling machine at 3000 mm/min. Fig. 13a Power profile for Takisawa Mac-V3 milling machine during air cutting of slot at 0 degrees with feedrate of 3000 mm/min Fig. 13b Power profile for Takisawa Mac-V3 milling machine during air cutting of slot at 30 degrees with feedrate of 3000 mm/min Fig. 13c Power profile for Takisawa Mac-V3 milling machine during air cutting of slot at 90 degrees with feedrate of 3000 mm/min Predicted power requirements for feed axes at 3000 mm/min when tool is executing linear interpolation at 0, 30 and 90 were estimated to be 3189 W, 3486 W, and 3537 W respectively. The measured power of the feed axes from the Fluke 434 power quality analyser gave 3510 W, 3702 W, and 3723 W for the aforementioned angles respectively. Thus, the deviation between the model and the measured power demand of the feed axes for the specified angles were between 5 % and 9%. The wide difference in the deviation may be due to the fact that the model does not capture the dynamic characteristics of the machine tool. More acceleration forces are required to actuate the feed drive at higher feedrates which result in feed axes power requirement increase. Additionally, the energy required by the feed axes to execute a linear toolpath during air cutting can be estimated using Equation 10. Consequently, the results of some of the predicted and measured energy demand of the feed axes during air cutting are presented in Table 7. Table 7 Predicted and Measured energy demand of the feed axes