Temperature Measurement of Wire Electrode in Wire EDM by Two-color Pyrometer

In wire electrical discharge machining (EDM), it is considered that one of the major reasons why the wire electrode breakage occurs is the increase of temperature of wire electrode during machining. This is because the increase of the temperature leads to the decrease in the mechanical strength of wire electrode. However, the temperature of wire electrode has not been directly measured because it is difficult to measure the temperature by conventional measuring methods such as a thermocouple. Therefore, in this study, a two-color pyrometer with an optical fiber was used in order to measure the wire temperature during wire EDM in mist. Experimental results showed that the temperature of the wire electrode could be measured by the two-color pyrometer if the temperature was higher than 100 °C. Wire EDM was performed using a mist nozzle, and the temperature measurement of the wire electrode was attempted. Experimental results showed that the output of the two-color pyrometer was not observed, which indicated that the temperature of the wire electrode was lower than 100 °C under the experimental conditions used in this study.