This paper discusses the stability of high-speed machining processes. The problem of harmful vibrations can usually be detected based on measured signal forces. Nevertheless, the chatter effect may be unrevealed and hence some alternative approaches of signal monitoring must be taken to detect it. In the discussed case of machining, process stability is determined by means of stability diagrams. The measured milling force components are investigated by various signal analysis methods. In addition to this, the analysis also uses recurrence plots, recurrence quantifications, composite multi-scale-entropy and as well the statistical approach. Results obtained by the different methods are presented and discussed.