Nizhny Novgorod State Technical University named after R. E. Alekseev, Nizhny Novgorod, Russia

I. O. Leushin, Dr. Eng., Prof., Head of the Dept. of Metallurgical Technologies and Equipment, e-mail: igoleu@yandex.ru
L. I. Leushina, Cand. Eng., Associate Prof., Dept. of Metallurgical Technologies and Equipment, e-mail: kafmto@mail.ru
O. S. Koshelev, Dr. Eng., Prof., Dept. of Mechanical Engineering Technological Complexes, e-mail: kos7shef3@yandex.ru
P. A. Gorokhov, Postgraduate Student, Dept. of Metallurgical Technologies and Equipment, e-mail: pavel_goroxov@mail.ru

Lost foam casting is one of the most popular special types of casting, in which the material of a nonremovable disposable casting pattern is gasified under influence of the thermal energy of the metal poured into the pattern, coming into direct contact with it. Traditionally, polystyrene foam is used as a material for casting patterns, which has such disadvantages as intense gas evolution upon contact with a metal melt and a high probability of surface defects appearing on castings due to the deposition on the pattern walls of a large amount of sooty coke residue formed as a result of pattern gasification. The authors focus on the issue of choosing the optimal composition for the manufacture of disposable lost patterns applicable in the production of machine parts workpieces from cast iron by casting. The basic requirements for the material of the patterns were formulated, an informational and analytical review of the state of the issue was carried out, the most probable chemical reactions of thermal destruction of some polyplastics were analyzed, experimental studies and pilot testing of the results obtained in the conditions of the existing foundry were carried out. For the manufacture of disposable lost patterns in cast iron production, a material is proposed that is a composition of polypropylene, polymethyl methacrylate and a foaming agent. It does not contain scarce and expensive components, is characterized by high manufacturability, enables to produce patterns in a short time with minimal labor intensity and ensure the production of high-quality castings in terms of structure, mechanical properties of cast iron, surface defects and gas porosity without deteriorating the working conditions of production personnel.

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