Chatter identification methods on the basis of time series measured during titanium superalloy milling

• Recurrence plot and Hilbert–Huang transform characterise milling process dynamics.
• Recurrence quantification analysis can be used to define stability index.
• Entropy and some statistical parameters can be also applied to recognise chatter.

The paper discusses the problem of stability in the milling process of titanium super-alloy Ti6242. Although this problem is often considered theoretically, theoretical findings do not always agree with experimental results. For this reason, the paper presents the methods for stability estimation in real milling processes. First, a stability lob diagram is created based on parameters determined in impact testing of an end mill. Next, the cutting forces are measured in an experiment where the axial cutting depth being gradually increased. Finally, the obtained experimental data is analysed with respect to stability using the recurrence plot technique and the Hilbert–Huang transform.