Pressure Distribution in the Air Film and the Porous Conveyor Air Bearing

Abstract

The porous aerostatic conveyor bearings are used to feed large substrates such as the flat panel display glass sheets and the silicon wafers by supporting them with compressed air in a non-contact condition. Due to unevenly distributed pressure in the air film between the substrate and the porous aerostatic conveyor bearing, the soft substrate often deforms and tilts on the bearing pad during the feeding process. In order to investigate the pressure distribution in the air gap, the CFD software, FLUENT, was employed to simulate the operation of the porous aerostatic conveyor bearing during the feeding process. In addition, the load capacity of the conveyor air bearing was calculated. The results show there is low vacuum pressure around the air discharge holes. The high pressure above the air supply holes forms two paraboloidal distributions in the air film. For design modification, the air supply and the air discharge holes need to be rearranged and/or relocated to improve the pressure distribution in the air film for more stable feeding of the substrate.