Rolling guideways are widely used in machine tools. In rolling guideways, rolling elements move raceway groove between rail and carriage. Commonly, rolling guideways have two or four rows, eight rows' are getting a lot of attention as high rigidity and damping. Eight-row guydeways have more and smaller rolling elements than others. However, the influence of the number and diameter of balls on its damping has not been clarified. Thus, this paper describes the influence of number and diameter of balls on its damping using damping measurement apparatus. In this apparatus, it is possible to measure the influence of design variable of rolling guideways respectively. In consequence, the number of balls is more relevant to dynamic characteristics of rolling guideways than diameter of balls.
