Electrical Porcelain Body (..contd):
The raw materials like Clays are blunged separately, the non-plastic materials like Feldspar, Quartz and Talc are dry ground or wet ground. The plastic clays and the non-plastic ground materials are mixed together to prepare a liquid slurry. This slurry is then passed through sieves and magnets and stored in storage tanks. Here the slip is kept for aging for almost 72 hours. After aging the slip is passed through filter press, where it is pressed into cakes. The cakes are then dried in toast racks to the required moisture content of 13%-16% and pressed into different shapes.
In some companies the cakes are ground in grinding pans with perforated bottoms to form a coarse dust which is stored in silos and then fed into pressed through belt conveyors. Alternative methods are to pass the filter cakes through pug mills which extrude small rods. These are then passed through a dryer by belt conveyors to remove the moisture and then ground into powder.
Various types of presses are used for shaping. Processes like Casting, Jolleying, and Turning are used for making different shapes. The products are fired at 1250oC.
..to be contd
