Improved dynamic cutting force modelling in micro milling of metal matrix composites Part I: Theoretical model and simulations
Zhichao Niu, Kai Cheng
Abstract
Cutting force modelling for micro machining is of great importance for better understanding of the cutting mechanics in the process. As precision machining of metal matrix composites (MMCs) is much more complex than machining homogeneous materials, the accurate prediction of cutting force is critical to control the cutting performance and tooling life. This paper presents an improved theoretical dynamic cutting force model in MMCs micro milling process by using straight flute PCD end mills. The theoretical model is modified and improved based on the conventional milling force modelling while taking account of various factors including tooling geometries, the material microstructure, size effect and chip formation in the cutting process. An innovative expression on dynamic cutting force in micromachining MMCs is presented through the multiscale modelling and analysis. The cutting force coefficients are further defined through instantaneous cutting force signals analysis. Simulation results under varied cutting process variables are presented against a series of MMCs micro milling trials, which indicate that the improved dynamic cutting force model can predict the cutting force accurately and reveal more details on the cutting force variations in the process due to the material inhomogeneous nature. In addition, the optimal process variables can be readily explored through the dynamic force modelling and simulations so as to further improve the cutting performance.