Effectiveness of minimizing cutting fluid use when turning difficult-to-cut alloys

The environmental impact of lubricants is a key issue towards sustainable manufacturing. Even if dry cutting can be identified as the ultimate goal to achieve, lubrication is still a hardly surmountable industrial standard when machining difficult-to-cut alloys. In order to reduce the pollutant emissions and the problems related to the workers' health, alternative systems as Minimum Quantity Lubrication (MQL) or Cooling (MQC) have been emerging over the years. This research aims to investigate the machinability of a Ti-48Al-2Cr-2Nb (at. %) alloy, applying low cutting fluid (water and emulsion) volumes to the cutting area in the form of a precision-metered droplets mist. The results in terms of tool wear/life, surface quality, lubricant consumption, and environmental impact are discussed with reference to those of MQL, wet and dry cutting. The experimental evidences show that, as far as tool life is concerned, the use of an emulsion mist is an advantageous strategy in comparison to MQL and dry cutting. Moreover, the flow rate and the type of cutting fluid are variables significantly affecting the process performance.