Laboratory Versus Industrial Cutting Force Sensor in Tool Condition Monitoring

Research work concerning the utilization of cutting force measurements in tool condition monitoring usually presents results and deliberations based on laboratory sensors. These sensors are too fragile to be used in industrial practice. Industrial sensors employed on the factory floor are less accurate, which must be taken into account when creating a tool condition monitoring strategy. Another drawback of most of this work is that constant cutting parameters are used for the entire tool life. This does not reflect industrial practice where the same tool is used at different feeds and depths of cut in sequential passes. This paper presents a comparison of signals originating from laboratory and industrial cutting force sensors. The usability of the sensor output was studied during a laboratory simulation of industrial cutting conditions. Instead of building mathematical models for the correlation between tool wear and cutting force, an FFBP artificial neural network was used to find which combination of input data would provide an acceptable estimation of tool wear. The results obtained proved that cross talk between channels has an important influence on cutting force measurements, however this input configuration can be used for a tool condition monitoring system. INTRODUCTION Increasing use of tool and process monitoring systems is one of the most significant developments in the manufacturing environment 12, 3/. Sensors most commonly used in such systems measure cutting force components or quantities related to cutting force /4, 5/. They are relatively easy to install on existing or new machines and work well in harsh machine tool environments. In most research reports, however, laboratory cutting force sensors are used, despite the fact that they cannot be used in factory floor practice /4/. It is, therefore, important to compare the applicability of cutting force measurements obtained using a laboratory sensor with those from a high-quality industrial sensor.