Investigation on Direction Dependency of Tool-Workpiece Compliance of Machine Tool

The direction dependency of tool-workpiece compliance of machine tool was investigated in three dimensions. The tool-workpiece compliance is defined as the frequency response of the relative displacement between the tool and the workpiece to the cutting force. The tool-workpiece compliance of a vertical type machining center was measured. The direction dependency of the compliance magnitude was discussed using the polar plot. The compliance in the Z (vertical) direction was smaller than that in the XY (horizontal) directions. The maximum value of the compliance in the X direction was almost twice as large as those in the Y and Z directions. The influence of the frequency on the direction dependency was also discussed. The direction dependency in the XY plane was small in the frequency range higher than 250 Hz. This can be explained by the symmetry of the spindle about the X and Y directions because the tool-workpiece relative displacement was dominated by the tool displacement in the high frequency range