For ultra-precision machine tools, hydrostatic bearings are the key components to determine the machining accuracy. This paper deals with a design method to determine optimum restrictor that maximizes the stiffness of water hydrostatic bearings. A short-pipe model of the restrictor is tested by comparison with the experimental results, showing good agreements with the prediction by the derived model. Introduced mathematical model is used to derive a useful equation representing the optimum aspect ratio of the short-pipe restrictor. It is noted that the equation is defined with newly defined non-dimensional parameters. Based on the derived equation, the paper also provides a useful graph in which the designer can easily find out the optimum aspect ratio of the restrictor for their hydrostatic bearings so that the bearing stiffness can be maximized.
