Ceramics Production in the New Millennium

Use of casting under pressure for sanitary ware production is a patented manufacturing technology of Laufen, being used since 1985. Laufen CZ operates nine production lines of this type in the Czech Republic. At the moment there is one such line in Znojmo (washbasin production), and eight lines in Bechyně (cisterns, toilets, and washbasins).

Casting under pressure is based on the use moulds made of porous plastic; moulds consist of two to four parts, depending on the complexity and shape of the final product. One mould can be used to make 35 to 40 thousand products, and therefore it can last much longer than a plaster mould, which must be replaced after every 90 to 100 castings.

At first, a mould for casting under pressure is pre-filled with the casting slip with the temperature of 40 to 43 deg. Celsius (the so-called DITURVIT) under the pressure of 3 to 4 bars; the pressure is raised to 10 to 12 bars when the filling is completed. Casting slip, which is a mixture of water, clay, kaolin, feldspar, silica sand, and an additive of finely ground pieces of ceramic scrap, starts to form into a ceramic body. By applying the pressure, material adheres to the surface of the mould, while water drains away through porous walls of the mould. After producing a ceramic body 9.0 to 9.7 mm thick, excess casting slip in the mould is drained away, letting the moulded piece solidify under the pressure of 2.5 bars. Moulded piece is then removed, dressed (holes are made, excess material is cut off), and pre-dried in the microwave kiln. After pre-drying, the moulded piece is again dressed, checked for flaws, and final dried, so that it could be glazed and baked.

Manufacturing technology utilising die casting to produce ceramic bodies is undoubtedly a technology of the future. Laufen CZ is fully aware of the advantages of casting under pressure, and it is considering launching of additional production lines of this type. Procurement of this manufacturing technology represents a large investment, although a returnable one, in form of higher quality production and longer life-span of casting moulds.

Manufacturing process visualization

Casting, ceramic body formation

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Drying, glazing, baking

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Final inspection, packaging

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