Infrared measurement of the temperature at the tool-chip interface while machining Ti-6Al-4V

Abstract

The challenges associated with machining titanium alloys (e.g. Ti-6Al-4V) are directly related to high cutting tool temperatures due to the low thermal conductivity of titanium alloys and the heat generated in the primary shear zone and at the tool-chip interface. Measurement of the temperature at this interface is performed using an infrared camera and a transparent cutting tool while orthogonally machining Ti-6Al-4V. The high frame rate (700 Hz) and large field of view (20 mm^2) used in this study enable the temperature distribution of the interface to be measured and the chip curl and breakage to be observed while cutting with a feed rate of 50 m/rev and cutting speeds between 20 m/min and 100 m/min. In addition to the temperature measurements, cutting forces are recorded and the chip formation is documented using a high speed (3 kHz) visible light camera. Results show that apparent temperature increases with speed while the cutting and thrust forces show no significant cant trend. Analysis of the temperature distribution from one edge of the chip to the other reveals differences from 6% to 21%, indicating that caution must be used when performing thermographic measurements from the side of the cutting zone. Post process measurements of the tool condition reveal at minimum a possible correlation with the measured temperature distribution and at most a need to account for the tool condition when converting the apparent temperatures into true temperatures.