INDIRECT TOOLTIP FREQUENCY RESPONSE FUNCTION MEASUREMENT: AN APPLICATION OF SURFACE LOCATION ERROR

Milling is a well-established manufacturing process thanks to its accuracy and surface finishing, yet tool vibrations limit these qualities. At the core of many approaches dealing with vibrations the tool-tip frequency response function (FRF) is found allowing the computation of the appropriate cutting conditions for accuracy and stability. The evaluation of the tooltip FRF is often based on experimental modal tests which require additional sensors to be mounted on the machine tool as well as devices to excite the tool. However, the reliability of these methods is strictly related to the test setup and the expertise of the operator performing the measurement. This paper presents a methodology to evaluate the tooltip FRF starting from the surface location error (SLE) without requiring additional sensors or experienced operators. The method is based on a frequency domain cutting force model coupled with the SLE measured at different spindle speeds using on-machine measuring probe. The methodology was experimentally tested to check its effectiveness and limitations.