【正文】 f cut and width of cut of 2 mm and 4 mm, respectively, was used. The chip load of mm/tooth was maintained constant across the experiments, to allow for the parison of the Sustainability in Manufacturing Energy Efficiency in Machine Tools results. The process parameters used in the experiment are outlined in Table 3. Table 3: Process parameters for power demand experiments with multiple work piece materials. The remended cutting speed varied with the work piece material. Aluminum was cut at the highest speed, followed by polycarbonate, then steel. The use of coolant while machining aluminum was remended by the cutting tool manufacturer due to the material’s ductility and its tendency to buildup on the cutting tool. Coolant was also remended for polycarbonate to prevent it from melting because of the high temperature at the cutting tool and work piece interface. Steel can be cut without coolant (which would greatly reduce the total power demand of the machine tool), but since cutting fluid aids with chip exit and this study is primarily concerned with the cutting power demand, coolant was used when cutting all material types.The power demand of the NV1500 DCG is shown in Figure 6 , and is broken down into cutting and air cutting power demand. The air cutting power demand is approximately the same across the three processing conditions. The difference is due primarily to the change in spindle speed, the highest of which was used while cutting aluminum. The difference in the power demanded by the axis drives was found to be negligible even though the feed rate for aluminum is more than two times that of steel.The cutting power demand shows greater variability for the three work piece materials. The cutting power was the greatest while machining the steel work piece. In fact, it was approximately 7% of the total power demand. This may be due to the fact that it has the highest tensile strength, followed by aluminum, then polycarbonate. The cutting power while machining the polycarbonate work piece was the smallest and almost negligible, only 1% of the total power demand. Figure 6: Power demand of NV1500 DCG for steel, aluminum, and polycarbonate work pieces.Sustainability in ManufacturingEnergy Efficiency in Machine Tools A particular work piece material can be machined at a range of process parameters while maintaining minimal tool wear and good surface finish. So future experiments should be conducted in which the material removal rates overlap as much as possible across the work piece materials under study when calculating the cutting power demand for the purpose of parison. Also, the power demand of the spindle motor and the axis feed drives should be measured directly since presently the cutting power demand is obtained by subtracting the air cutting power demand from the total power demand of the machine tool. 5 CONCLUSIONS This study has shown that the machining time dominates energy demand for high tare machine tools. Additionally, it has provided a method for characterizing the specific energy of a machine tool as a function of process rate, which can be extended to other types of manufacturing processes. The specific energy model allows a product designer to estimate the manufacturing energy consumption of their part’s production without needing to measure power demand directly at the machine tool during their part’s production. Since the specific energy as a function of . for the micromachining center presented herein varied by as much as an order of magnitude, it is important to use process parameters and machine toolspecific data to determine accurate electrical energy consumption. This model could therefore be used in place of aggregate embodied energy values for manufacturing processes as provided by [9] or to replace process estimates with great uncertainty when conducting hybrid life cycle assessments.6 ACKNOWLEDGMENTS This work was supported in part by Mori Seiki, the Digital Technology Laboratory (DTL), the Machine Tool Technologies Research Foundation (MTTRF), Kennametal, and other industrial partners of the Laboratory for Manufacturing and Sustainability (LMAS). The authors would like to thank the UC Berkeley Mechanical Engineering Department’s Student Machine Shop for providing valuable insight and advice . For more information, please visit . 7 REFERENCES [1] Diaz, N.。 Jarvis, A.。迪亞茲，艾琳娜 負荷切削剖面正如迪亞茲在參考文獻[3]里所描述的那樣，一臺機床的能耗由切削能耗、變量能耗、恒定能耗元件的能耗組成。當工藝參數的選擇原理推薦條件時，刀具磨損和刀具成本顯著增加。由于機床的空切功率為1510W，增加了材料去除率后的能量消耗也只是增加了28%而已。像之前提到的一樣，平均電能消耗量由切削電能消耗P cut和空切P air兩個部分組成。所以，在以上這些約束條件下得到的材料去除率可得到以下形式的一條曲線： (7)這條曲線與數據寬度切和切削深度的實驗結果吻合。4 工件材料對電力需求的影響上述實驗是用材料為低碳鋼的工件進行的。表3是實驗的加工工藝參數。在材料去除率低于75mm?3/s時，一些微小的材料去除率增量都可以使得比能量大幅下降，因為加工時間顯著的減少了。 (4)如果空切電能消耗量的相對比率用下式表示： (5)系數i為1或2分別代表方案1和方案2，不等式（6）為方案2比方案1節(jié)能必須滿足的條件。用直徑為8mm，兩齒的無涂層硬質合金立銑刀和錫涂層兩齒硬質合金立銑刀在同樣的開槽切削條件（）。切口是在長度為101毫米的1018鋼件上用直徑為8毫米的立銑刀以2毫米的切削深度沿著Y軸方向進行切削。本文涉及到材料去除率對能源消耗的影響。消費品在其使用期中被其使用階段所支配，這些消費品包括燈泡、計算機、冰箱和汽車等這些被廣泛使用的日常用品。 Hideta, M.。 Choi, S.。 Specific Energy CharacterizationAbstract:Since machine tools are used extensively throughout their functional life and consequently consuming valuable natural resources and emitting harmful pollutants during this time, this study reviews strategies for characterizing and reducing the energy consumption of milling machine tools during their use. The power demanded by a micromachining center while cutting low carbon steel under varied material removal rates was measured to model the specific energy of the machine tool. Thereafter the power demanded was studied for cutting aluminum and polycarbonate work pieces for the purpose of paring the difference in cutting power demand relative to that of steel.