Fiber-Optic Pyrometer for Very Localized Temperature Measurements in a Turning Process

A fiber-optic two-color pyrometer based on glass multimode fibers with 62.5 mu m diameter and 0.275 numerical aperture is used for localized temperature measurements in turning processes. Operation wavelengths improve temperature measurement accuracy. The system is capable of measuring temperature in the range from 300 to 650 degrees C in a surface area below 0.16 mm(2). Numerical simulation of the calibration curves including manufacturer tolerances are reported, showing good agreement with the experimental results. Temperature evolution is performed in a lathe at different feed rates and cutting speeds at an Inconel 718 turning process, using a glass fiber-optic sensor embedded into a modified tool member. The results are used to in-process prevent premature failure of the components related to the fatigue and validate feed rates recommended by the tool manufacturer.