Spindle speed ramp-up test: A novel experimental approach for chatter stability detection

Chatter is one of the most limiting factors in improving machining performances. Stability Lobe Diagram (SLD) is the most used tool to select optimal stable cutting parameters in order to avoid chatter occurrence. Its prediction is affected by reliability of input data such as machine tool dynamics or cutting coefficients that are difficult to be evaluated accurately, especially at high speed. This paper presents a novel approach to experimentally evaluate SLD without requiring specific knowledge of the process; this approach is called here Spindle Speed Ramp-up (SSR) test. During this test spindle speed is ramped up, and chatter occurrence is detected by the Order Analysis technique. As result one single test ensures optimal spindle speed identification at one cutting condition, while if few tests are performed the entire SLD could be obtained. Results of the method applied to slotting operation on aluminum are provided and a comparison between different measurements devices is presented. This quick, easy-to-use and efficient test is suitable for industrial application: no knowledge of the process is required, different sensors can be used such as accelerometer, dynamometer or microphone.