Abstract

Planarization of silicon wafer is necessary for photolithography or thinner process.Therefore polishing process and grinding process are carried out.In such processes,hydrostatic bearings are needed as bearings of rotary tables of grinding machines.In this case,higher bearing stiffness is significantly important to achieve precise grinding.Bearing restrictor is a part of the most important elements of hydrostatic bearing.Bearing performance is significantly affected by the dimensions of restrictors.Design of the restrictors of a hydrostatic thrust bearing maximizing bearing stiffness is considered in the paper.In particular,the paper focuses on a design of restrictors used in the hydrostatic thrust bearings sustaining vertical loads.In such cases the table supported by the bearing moves from its neutral position due to gravity force.Numerical analysis indicates that an achievable highest stiffness for various bearing positions can be represented by an envelope curve derived.Using proposed design procedure,the bearing stiffness of our water hydrostatic thrust bearing becomes 1.5 times of that of the previous design at given operational condition.