The difficulties with the identification of the cutting process under real cutting conditions forced the majority of previous experimental work to be directed to orthogonal cutting. However, the complexity of the test equipment and either of the low accuracy or the long calculation time for data processing techniques limited the reliability and the amount of the available experimental results. To overcome these problems two multivariate time-series analysis methods are presented and their accuracy and convenience for the identification of the cutting process are discussed using simulated and actual data. Both methods were used to identify the transfer functions between the cutting forces and the feed-direction tool-workpiece relative vibrations under three-dimensional cutting conditions. Information about the test rig and frequency responses of the transfer functions is given.