Development of a fine tool servo with force monitoring system for nanomachining applications

The strong demand for ultraprecision components in today's industries has gradually delivered focus in the research area of diamond turning. A new technique called tool servosystem, an auxiliary servoaxis of the lathe, has become the best solution in machining the ultraprecision surfaces more effectively. This article presents a newly developed piezoelectric-based fine tool servo (FTS) system for a miniature ultraprecision lathe. The FTS system is specially designed by installing a small-size and high sensitivity force transducer which measures the thrust force along the in-feed direction during diamond turning, and also detects the initial contact point of tool/workpiece. A new flexure mechanism of the FTS is presented which is built to measure the cutting force and guide the piezoelectric actuator movement. By employing this flexure mechanism, the cutting force can be measured accurately without sacrificing the desired displacement of the cutting tool during turning process. In order to achieve the optimized tracking performance, the FTS system is controlled by the proportional-integral-derivative feedback and feedforward algorithm that is available with the motion controller. The nonferrous workpiece materials such as aluminum alloys and brass have been machined in this study to investigate the performance characteristics of the developed FTS system. In addition, an example of a nanosurface with microfeatures has been machined and thereby successfully verified the capability of the FTS system. The results show a significant improvement in the surface finish of the machined workpiece and also confirm that this system can successfully generate nanosurfaces effectively.