High Speed Drilling and Tapping using the Technique of Spindle Through MQL Supply

The minimal quantity lubrication (MQL) technique is used in cutting processes in order to reduce the environmental pollution caused by cooling lubricants. In the usual case of MQL cutting, the oil mist is supplied to the cutting area by external supply nozzles. In the case of a high speed cutting process, however, the high speed peripheral air flow prevents the oil mist from reaching the cutting area. The spindle through coolant supply method gives a good solution to this problem. However, the small oil drops could stick to the inside of the rotating duct, separated from the air flow during high speed spindle rotation exceeding 10000 rpm, and do not reach the cutting point unless the spindle speed is reduced. In this study, a new spindle through lubricant supply system for MQL high speed cutting was developed and installed in a high speed spindle system. The performance of the developed system was evaluated by carrying out high speed drilling and tapping operations for aluminum alloy.