Minimum quantity lubrication (MQL) drilling has been known for decades, but limited knowledge is available on two-channel through-tool MQL drilling due to the lack of accessibility to production systems. A common problem in MQL drilling is the absence of a rational approach to select the oil flow rate. The limited entry and exit area, and fixed energy available to the flow make the behavior complicated. This study leverages the capabilities in Ford’s manufacturing lab to abridge the research gap. Four different oil flow rates (0 ml/h, 15 ml/h, 30 ml/h and 60 ml/h) and two different drills (twist drill and straight drill) were used to find out the influence of oil flow rate on the cutting performance. Tool life, tool wear, cutting force and torque were monitored as the cutting performance indicators. It was concluded that, the common belief of higher oil flow rate providing better tool life, does not hold true for through-tool MQL drilling. The tool life for 30 ml/hr. oil flow rate appeared to be the highest compared to all the other cases for both the drills. Increasing the oil flow rate above 30 ml/hr. decreased the tool life. However, it is to be noted that the optimal oil flow rate values may be specific to the case.

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