Nizhniy Novgorod State Technical University (Nizhniy Novgorod, Russia):

L. I. Leushina, Cand. Eng., Associate Prof., the Chair “Metallurgical technologies and equipment”
I. O. Leushin, Dr. Eng., Prof., Head of the Chair “Metallurgical technologies and equipment”, e-mail: igoleu@yandex.ru
O. S. Koshelev, Dr. Eng., Prof., Chair “Engineering technological complexes”, e-mail: kafmto@mail.ru

A variant of intensification of the process of smelting air-containing paraffin-stearine model compounds in hot water as a part of the of precision steel castings production has been described. The risks of the traditional process of smelting the model composition in hot water, associated with the repeated use of the material of the smelted models in the alkaline environment of a heating bath, as well as with the saponification of stearine in hot tap and hard water, were considered. A set of measures has been proposed aimed at reducing the duration of the smelting process, reducing the residual content of the model composition in shells in the end of the process and reducing these risks. The main role in solving this problem is assigned to the regulation of the hydrogen index values in the smelting bath and to sodium lauryl sulfate as a surface-active additive in the coolant. The most important feature of this cleaning agent widely used in industry is its amphiphilicity — the property of a molecule to have both hydrophilic and hydrophobic properties, which ensures a decrease in surface tension, an increase in wettability in the contact zone of the coolant with the melted model composition, and also the creation of conditions for solubilization and partial colloidal dissolution of the model composition in the activated coolant. A detailed description of the successful pilot testing of the development in conditions of existing production of one of the plants is given. Its results can be recommended to a wide range of stakeholders. The expected effects of implementation include the possibility of reducing the duration of the model composition smelting stage the (which is especially important for mass production), as well as reducing the residual content of the model composition in the shells in the end of the process (important regardless of batch) and, as a consequence, stabilization of the investment casting process and castings quality assurance.

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