Determination of Thermophysical Properties for Selected Molding Sands

M. Łągiewka Częstochowa University of Technology, Faculty of Production Engineering and Materials Technology, Institute of Metallurgy and Metals Technology, Częstochowa, Poland

Received: August 26, 2019; revised version October 1, 2019; in final form October 2, 2019

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This article presents results of the research, which allowed to study the main thermophysical properties of the oil-bonded molding sand and bentonite, i.e., the temperature equalization coefficient a2 and the heat accumulation coefficient b2 in the selected points of the casting mold. The method used to determine the coefficients a2 (thermal diffusivity) and b2 by measuring the temperature of the mold, allows simple and accurate calculation of these coefficients. The coefficients of heat transfer α1 and heat accumulation in molding b2 state the ability to remove heat from the casting. As the volume (mass) of the mold increases, the amount of heat accumulated in the mold increases. Affecting the value of these indicators by selecting the composition of the molding sand and the method of preparing the mold for flooding, the heat flow rate from cast to mold can be regulated to a certain extent, i.e., affect the rate and time of solidification of the cast, which can have an obvious impact on the structure and properties of the cast. Based on the conducted tests, it was found that the values of coefficient b2 differ from the value of this coefficient calculated on the basis of literature data, which allows to state that the theoretical calculation of the heat storage coefficient of molding sand is not sufficient and reliable and that these calculations should be verified experimentally.

DOI:10.12693/APhysPolA.136.992 topics: theoretical basis of casting processes, molding material, oil binder, heat accumulation coefficient for molding sands, temperature equalization coefficient\\vs*{7pt}