Green cutting strategy – how to perform turning with least energy expense?

Removing material in turning is and energy intensive task. However the energy consumption can depends on the chosen processing strategy. Shifting parameters can have a profound effect on overall efficiency. In my recent study I quantitatively investigated the effects on depth of cut, feed and cutting speed have on the energy requirements.

The plots below show how the operating conditions affect the overall efficiency of a direct drive spindle-chiller assembly in turning operation (considered cutting diameter – 20%). For the elaboration an analytical model identified on a DMG Mori lathe was used.

The relationship is not trivial, therefore an numerical optimization methods were employ to maximize efficiency for a range of possible diameters and material removal rates. The results are interesting! It seem that for small diameter (up to around 40-45mm) bars it is more efficiency to actually reduce the processing speed. In this case we’ll save on speed-dependent friction losses and restive losses due to synchronous-motor field weakening. Similarly for largest diameter where slow rotational speed and high load of the spindle cause significant copper losses. In this case it is also suggested to reduce the processing speed. For the mid-range diameter bars – the fastest processing rates are to most efficient.

Contents of this article is just a small extract from the work published in a journal:
“Wójcicki, J., Leonesio, M., & Bianchi, G. (2018). Integrated energy analysis of cutting process and spindle subsystem in a turning machine. Journal of Cleaner Production170, 1459-1472.”

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