Experimental stability lobes identification method based on time-frequency domain analysis

Chatter is one of the main limitations to milling performance. The main tool adopted to identify this detrimental phenomenon is Stability Lobe Diagram (SLD), a chart by means of which optimal machining parameters can be forecasted and hence selected. However its prediction is affected by reliability of input data, i.e. machine tool dynamics and cutting coefficients, hard to be accurately estimated, especially at high speed. This paper presents a novel technique to experimentally evaluate SLD: this approach is called Spindle Speed Ramp-up (SSR) test. During this test spindle speed is ramped-up and chatter occurrence is detected thanks to a time-frequency domain technique (i.e.,Order Analysis). As a result only one test ensures optimal spindle speed identification at one cutting condition, if few tests are performed the entire SLD could be obtained. Results of the method applied to slotting operation on aluminum are provided in case of single chatter frequency and multi chatter frequencies occurrence. Proposed approach is suitable for industrial application: it is easy-to-use, fully experimental and does not require knowledge of the process and the vibration phenomenon. Moreover this technique could be used to investigate machine tool dynamics changing with spindle speed.