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The Influence of Silica Sand Granulometry and Sorting Level on Thermal Expansion

M. Bašistová P. Lichý

Archives of Foundry Engineering | 2023 | vol. 23 | No 3 | 12-15 | DOI: 10.24425/afe.2023.144309

Keywords Foundry sand Dilatometry Sand grains distribution Sieve analysis Moulding mixtures

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Abstract

The quality of the castings depends, among other influences, on the quality of the moulding mixture used. The silica sands used are characterized by high thermal expansion compared to other sands. The tendency to dilatation of the moulding mixture can be influenced by the choice of the granulometric composition of the basic sand and the grain size. The aim of this work is to present the influence of grain distribution of foundry silica sand BG 21 from Biala Góra (Poland) and the degree of sorting (unsorted, monofraction, polyfraction) on the degree of thermal dilatation of the sand and thus on the resulting quality of the casting and susceptibility to foundry defects. For the purpose of measuring thermal dilatation, clay wash analysis was performed, sieve analysis of the sand was carried out, and individual sand fractions were carefully sorted. The measurements confirmed a higher thermal expansion in the case of monofractional sand grading, up to 51.8 %. Therefore, a higher risk of foundry stress-strain defects, such as veining, can be assumed.

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Bibliography

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[9] Beňo, J., Adamusová, K., Merta, V., Bajer, T. (2019). Influence of silica sand on surface casting quality. Archives of Foundry Engineering. 19(2), 5-8. DOI: 10.24425/afe.2019.127107.
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Authors and Affiliations

M. Bašistová

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ORCID:

P. Lichý

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ORCID:

VSB-Technical University of Ostrava, Faculty of Materials Science and Technology, Department of Metallurgical Technologies, Czech Republic

Mulling and its Effect on the Properties of Sand-Water-Bentonite Moulding Mixture

M. Gawronová Š. Kielar P. Lichý

Archives of Foundry Engineering | 2022 | vol. 22 | No 3 | 107-112 | DOI: 10.24425/afe.2022.140243

Keywords Bentonite Green sand mixture Mulling time Green compressive strength Cumulative mulling

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Abstract

Today, foundries are facing increasing demands for greener and more economical production while maintaining or improving the quality of the castings produced. The importance and use of green sand mixtures using bentonite as a binder are thus coming to the fore once again. They have the advantage of both eliminating the chemicalization of production and also allowing the immediate use of the already used mixture, including the binder, after adjustment of the composition and mulling. In order to maintain the quality of the resulting castings, it is necessary to monitor the properties of the moulding mixture through a series of laboratory tests. It is also essential to look at the processing quality of these mixtures, i.e. the combination of good mulling quality and efficient mulling time, which is often neglected. It is the quality of mulling and the effective mulling time that help to develop the bonding properties of the bentonite, improve the properties of the mixture, determine the efficiency of the muller and possibly reduce the time and energy required for mulling. The aim of this work is to present the effect of mulling on the properties of sand-water-bentonite mixtures. The properties studied are mainly the compactability, strength characteristics, moisture content of the mixture and the order of addition of raw materials.

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Bibliography

[1] Jelínek, P. & Mikšovský, F. (1985). Contribution to the evaluation of the efficiency of uniform green moulding mixture. Slévárenství. XXXIII (7), 268-274. (in Czech)
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[8] Jelínek, P. (2004). Binder systems of foundry moulding mixtures – chemistry of foundry binders. (1st ed.). Ostrava. ISBN: 80-239-2188-6. (in Czech)
[9] Weniger, C.E. & Volkmar, A.P. (1970) A new control tool: a graph for evaluating effectiveness of available bentonite within foundry system sand. AFS Transactions. 1970, 17-24.
[10] Kumari, A., Murari, A.K., Prasad, U. (2020). Prediction of Green Sand Moulding Properties Using Artificial Neural Network. In U. Prasad (Eds.), Advances in Science & Technology (pp. 39-52). India: Empyreal publishing house.

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Authors and Affiliations

M. Gawronová

e-mail:

ORCID:

Š. Kielar

P. Lichý

e-mail:

ORCID:

VSB-Technical University of Ostrava, Faculty of Materials Science and Technology, Department of Metallurgical Technologies, Czech Republic

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The Influence of Silica Sand Granulometry and Sorting Level on Thermal Expansion

Abstract

Bibliography

Authors and Affiliations

Mulling and its Effect on the Properties of Sand-Water-Bentonite Moulding Mixture

Abstract

Bibliography

Authors and Affiliations