Externally pressurized gas bearings are widely used in linear guide-ways for measuring machines and precision positioning systems. The number and the diameter of the supply orifices and their position strongly influence the characteristic of the pad. Usually during the design process of a pad a distributed parameters model is used to simulate the pressure distribution under the pad because it doesn’t exist a general formula suitable for all possible geometries. Analytical methods can be applied for simplified geometries to calculate static and dynamic performance of pneumatic bearings. Analytical and lumped parameters models are of faster implementation with respect to distributed parameters models and are easier to implement in the design process.
The present paper proposes different lumped parameters models to obtain the static and dynamic characteristics of pneumatic pads. These methods can be used in order to optimize the stiffness in correspondence of the operating conditions. Rectangular air pads of size 30×60 mm are considered. The results are compared with that obtained with a distributed parameters model to estimate the accuracy of the models.