Tool with a thin film stress sensor for measuring the stress on the rake face in orthogonal cutting

Abstract

The evaluation of stress and temperature on the tool faces during machining is very important for understanding the fundamental mechanisms of cutting processes, developing cutting tools, optimizing cutting conditions. Although cutting temperature has been often measured using the tool-chip thermocouple method, a two-color pyrometer, thermography, 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 a layer structure of coating on the rake face was developed for orthogonal cutting. The film sensor was made of manganin, a copper-manganese-nickel alloy having piezoresistive effect. The manganin was coated on the rake face of polished tool insert of silicon nitride 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. A trapezoidal distribution of normal stress, which had been reported for soft materials by photoelasticity method, was also obtained from the measured stresses in this study.

Keywords

• thin film stress sensor
• cutting tool
• manganin with piezoresistive effect
• orthogonal cutting
• stress change with cutting time