• Categories:Industry News
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• Time of issue:2020-11-03 14:00
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(Summary description)The use of clay of good quality in an automatic moulding system is one of the most important requirements. Normally, the following qualities are required of good-quality bentonite: •it should develop good bonding properties when mixed or mulled with sand and water in the correct proportion. •it should be able to resist reasonable heat influence so its bonding strength and plasticity properties are maintained. •it should give the moulding sand the correct consistency (mouldability) so that the sand can be conveyed, stored and handled in the correct way during processing. •it should enable the moulding sand to compensate for the thermal expansion of the silica grains, which counteracts casting expansion defects. •it should give the moulding sand the correct stability and plasticity so that perfect lifting of pattern plates can be accomplished. •it should make it possible for the sand to resist the influence from the heat shock so that it is still economical to reuse the moulding sand. •in moulding sand mixtures it should maintain sufficient sand bonding properties in dry and hot condition so that the metal can be poured without any risk of casting defects and so that the poured moulds may be correctly conveyed, and still it should be economical to reuse the return sand. •the moulding sand mixture should collapse readily after cast-ing and be reused. •it should be economical in terms of price, transport, delivery and storage.