Emissivity calibration for temperatures measurement using thermography in the context of machining

• We built an experimental device able to record both luminance and temperature of a sample surface without oxidation.
• We used this device to extract an emissivity curve depending on temperature for the 316L.
• We used the emissivity curve to calculate temperature fields during turning.
• We found interesting temperature levels closed to the tool edge.

This paper will present the infrared thermography principles applied to the thermal fields recording during orthogonal cutting of 316L stainless steel. This paper is divided in three parts. First, emissivity curve of 316L is extracted by warming up a sample and dividing recorded grey levels by black body ones. This first step requires the design of special equipment that allows controlling temperatures and atmosphere while recording. Next, the IR camera equipped with a microscope is integrated in a CNC lath to record grey levels while orthogonal cuttings of 316L samples. To finish, the recorded grey levels fields are then numerically post treated using homemade emissivity curve to plot the thermal gradient created during machining. All these works are important to increase the cutting analytical and numerical models accuracy especially in the thermal field prediction.