Modified Approach for Cutting Force Measurement in Face Milling Process

Abstract

In modern manufacturing processes, there is an ever increasing demand for higher productivity. The continuous demand for higher productivity and product quality asks for better understanding and control of machining processes by reducing machining time with the increase of cutting force and material removal rate. The variation in cutting force results in deflection in the tool and workpiece and which intern deteriorates geometrical accuracy. One of the methods of improving productivity and quality lies in fact, to develop monitoring system which can control and maintain the cutting force at a prescribed level by adjusting cutting parameters using adaptive control technique.

The cutting force is one of the important characteristic variables to be monitored in the cutting processes. This research paper consists of an indirect cutting force estimator during face milling process. Cutting forces and torque models are derived from cutting geometry in face milling process. The relationship between feed motor current and cutting forces has been developed from the proposed force models. Cutting forces are measured indirectly by sensing the currents of feed drive servomotors through the Fanuc SERVOGUIDE software. The instantaneous current data captured through the software is utilized for determining the instantaneous torque developed by the feed motor and instantaneous cutting forces have been estimated by using force and torque models. Practical issues calculating cutting force using motor current on a commercial machining center is also carried out.

The experimental methodology involved estimation of torque consumption by the motor, first during idle movement and second during actual machining of the component. The machining of the components using standard cutting condition has been carried out and the cutting force estimated using the above method were validated by comparing the cutting force data derived from an accurate dynamometer for similar cutting condition.

Practical experimental results are found to be in agreement with the estimated value to an accuracy of ± 10%. This proves indirect measurement is quite reasonable and economical and it has an important application value with high compatibility and stability.