Abstract
The contributor to the support stiffness of machine tools is investigated. In this paper, it is assumed that the support stiffness depends on the load on mounts of machine tools because the contact stiffness influences the support stiffness. In this case, even if the number of the mounts of machine tools changes, the total support stiffness in the vertical direction should not change. To verify this hypothesis, it is shown that the natural frequency of the vertical vibration mode is irrelevant to the number of the mounts. Moreover, it is verified that the real contact area is decided by the load and the hardness of the contact surface.