Effects of tool life criterion on sustainability of milling

Abstract

For the last ten years, sustainability has been the most important factor in readjusting the goals of metal cutting domain. Tool life and its attainment criteria have played a highly significant role in controlling the sustainability measures such as process cost, energy consumption, and work quality. The article presents an experimental investigation to study the effects of setting different levels of flank wear as tool life criterion on the sustainability measures of milling process. The metrics used in this work for measurement of process sustainability are specific energy consumption, process cost (including tooling cost), work surface roughness, and material removal rate. A total of 48 experiments were performed on two tempered forms of a cold work tool steel in order to quantify the effects of cutting parameters, tool life criterion, work material's temper state, and lubrication mode. It was found that tool life criterion possesses a very strong influence on all the sustainability metrics. A criterion allowing a tool to run longer is favorable for tool life and process cost while the one calling for early tool replacement suits the metrics of work surface quality and specific energy consumption. The effects of the other predictors on the sustainability metrics were also quantified and analyzed. Micro-chipping and adhesion were found to be the dominant modes of tool damage in the experiments involving the high levels of the cutting parameters and work material hardness. Finally, a multi-criteria decision making approach was used to optimize the milling process with respect to various combinations of the sustainability related objectives.