Thin Film Stress Sensor on the Tool Rake Face for Orthogonal Cutting

The evaluation of stress and temperature on the tool faces during machining is very important for understanding the fundamental mechanism of machining processes, developing cutting tools, optimizing cutting conditions. Although cutting temperature has been often measured using the tool-chip thermocouple method, a two-color pyrometer, etc., measurement of stress on the tool face has been hardly reported. For this reason, a cutting tool with a thin film stress sensor in the surface layer of the rake face was developed for orthogonal cutting. The film sensor was made of manganin, a copper-manganese-nickel alloy having piezoresistance effect. The manganin was coated on the rake face of polished silicon nitride matrix by magnetron sputtering in a specific pattern having a line 30 micrometer wide and 0.2 micrometer thick along the cutting edge. Then, the rake face was further coated with silicon nitride for protecting the thin stress sensor. After the calibration of the sensor, the tool was applied to orthogonal cutting experiment, in which MC Nylon and polyvinyl chloride were machined at a very low cutting speed. For four levels of uncut chip thickness from 0.05 to 0.20 mm the stress was measured for MC Nylon. The measured stress seems consistent with stress distributions measured by photoelasticity method reported so far.