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In the paper, presented are results of a research on influence of compaction degree on dielectric properties of components of moulding sands. During recent years, intensive research works on possibilities of using microwave heating in foundry technique are carried-out. However, introduction of such innovative, environment-friendly and efficient heating processes to foundry technologies is accompanied by a shortage of basic knowledge about behaviour of components of moulding sands in microwave field. In this case, of particular importance becomes knowledge of electrical properties of components of moulding and core sands, i.e. their permittivity εr and dielectric loss factor tgδ that characterise efficiency of absorbing electromagnetic radiation and thus prove effectiveness of the heating process.

The environment-friendly and cost efficient microwave heating of moulding and core sands opens possibilities to use plastics and wood for structures of foundry instrumentation, where transparency to microwaves is the main requirement. Presented are results of a preliminary research on determining possibilities to use selected materials in microwave field. From the viewpoint of specificity of this process, the basic parameter is ability to absorb or transmit microwave radiation. Determined were the following electrical properties: tangent of dielectric loss angle and permittivity of selected materials. The materials were classified according to their transparency to electromagnetic radiation in order to choose the ones suitable for tooling applied in foundry processes.