The lost foam process in castings

The paper discusses the thermal evaporation process of foundry pattern. At some research-development centers, studies carried out to examine the physico-chemical phenomena that take place in foundry mold filled with polystyrene pattern when it is poured with molten metal. In the technique of evaporation patterns, process the mold is filled with molten metal (the model is inside of a pattern polystyrene) interrelated with the process of thermal decomposition of the pattern. The process of evaporation polystyrene mold foundry pattern in molten metal under the effect of a kind of complex and depends on many different factors, not yet fully investigated.

The technology used in the manufacture of evaporative patterns of plates pilot castings high abrasion resistance. The material and the properties of the resulting castings were determined by the customer (patent protection). At the beginning of the study, a decision on the properties of the material pattern, was another stock, a decision on the properties of the ceramic layer as well as the preparation technique and application. Examined the technique of molten metal feeding the mold cavity as well as the parameters of the gating and feeding systems, and cooling solutions and solidification conditions (large shrinkage, shrinkage cavities and depressions). The technology of foamed polystyrene patterns thermally evaporated during manufacture of castings from ferrous alloys still find numerous obstacles on the way to a full practical use.

The difficulty level depends not only on the symptoms of the process itself, but also on the amount of intricacy pattern, model properties, and quality requirements imposed on projections. One of the main parameters to determine because the properly during the process of evaporative pattern of thermal decomposition kinetics of the foamed polystyrene pattern as well as the size and gas pressure are emerging from this pattern. Casting using the lost foam method used when small quantities have abrasion-resistant castings to be produced rapidly at low cost. This method was suggested as a possible choice for classical methods of molding sand. These elements must be characterized by high hardness (over 60 HRC) and high abrasion resistance. This article provides the results of this process in Lost Foam Casting plattes pilot.

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