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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

[1] Czerwinski, F. (2017). Modern aspects of liquid metal engineering. Metallurgical and Materials Transactions B. 48(1), 367-393. DOI: 10.1007/s11663-016-0807-6.
[2] Brůna, M. & Galčík, M. (2021). Casting quality improvement by gating system optimization. Archives of Foundry Engineering. 21(1), 132-136. https://doi.org/10.24425/afe.2021.136089.
[3] Monroe, R. (2005). Porosity in castings. AFS Transactions. 113, 519-546.
[4] Kowalski, J.S. (2010). Thermal aspects of temperature transformation in silica sand. Archives of Foundry Engineering. 10(3), 111-114. ISSN (1897-3310).
[5] Jelínek, P. (2004). Binder systems of foundry moulding mixtures – chemistry of foundry binders. (1st ed.). Ostrava. ISBN: 80-239-2188-6. (in Czech).
[6] Svidró, J., Svidró J. T., & Diószegi, A. (2020). The role of purity level in foundry silica sand on its thermal properties. Journal of Physics: Conference Series. 1527(1), 012039, 1-8. DOI 10.1088/1742-6596/1527/1/012039.
[7] Chao, Ch. & Lu, H. (2002). Stress-induced β→ α-cristobalite phase transformation in (Na2O+Al2O3)-codoped silica. Materials Science and Engineering: A. 328(1-2), 267-276. DOI: 10.1016/S0921-5093(01)01703-8.
[8] Hrubovčáková, M., Vasková, I., Benková, M. & Conev, M. (2016). Opening material as the possibility of elimination veining in foundries. Archives of Foundry Engineering. 16(3), 157-161. DOI: 10.1515/afe-2016-0070.
[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.
[10] Thiel, J., Ziegler, M., Dziekonski, P., Joyce, S. (2007). Investigation into the technical limitations of silica sand due to thermal expansion. Transactions of the American Foundry Society. 115, 383-400.

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Authors and Affiliations

M. Bašistová
1
ORCID: ORCID
P. Lichý
1
ORCID: ORCID
  1. VSB-Technical University of Ostrava, Faculty of Materials Science and Technology, Department of Metallurgical Technologies, Czech Republic

Evaluation of Mixing Efficiency and How it Affects the Properties of the New Green Sand Mixtures

Š. Kielar M. Bašistová P. Lichy
Archives of Foundry Engineering | 2023 | vol. 23 | No 3 | 88-93 | DOI: 10.24425/afe.2023.146666
Keywords Green sand mixture Eddy mixer mixing time Optimization of mixing Green compressive strength
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Abstract

The current trend in the preparation of green sand mixtures emphasizes the acceleration of the mixing process while maintaining the quality of the mixture. This requirement results in the necessity of determining the optimal conditions for mixing the mixture with a given mixer. This work aims to determine the optimal mixing conditions for the newly introduced eddy mixer LM-3e from the company Multiserw-Morek in the sand laboratory at the Department of Metallurgical Technologies, Faculty of Materials and Technology, VŠB - Technical University of Ostrava. The main monitored properties of mixtures will be green compressive strength and moisture of the mixture. The measured properties of the mixture mixed on the eddy mixer will be compared with the properties of the mixture mixed on the existing LM-2e wheel mixer. The result of the experiment confirmed that the eddy mixer is suitable for the preparation of a mixture of the same quality as the wheel mixer but with a significantly reduced mixing time.
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Bibliography

[1] Pastierovičová, L., Kuchariková, L., Tillová, E., Chalupová, M. & Pastirčák, R. (2022). Quality of automotive sand casting with different wall thickness from progressive secondary alloy. Production Engineering Archives. 28(2), 172-177. https://doi.org/10.30657/pea.2022.28.20.
[2] Kamińska, J., Stachowicz, M., Puzio, S. et al. (2023). Studies of mechanical and technological parameters and evaluation of the role of lustrous carbon carriers in green moulding sands with hybrid bentonite. Archivives of Civil and Mechanical Engineering. 23, 11, 1-19. https://doi.org/10.1007/s43452-022-00550-1.
[3] Radkovský, F., Gawronová, M., Merta, V., Lichý, P., Kroupová, I., Nguyenová, I., Kielar, Š., Folta, M., Bradáč, J., Kocich, R. (2022). Effect of the composition of hybrid sands on the change in thermal expansion. Materials. 15(17), 6180, 1-15. https://doi.org/10.3390/ma15176180.
[4] Troy, E. C. et al. (1971). A mulling index applied to sand-water-bentonite. AFS Transactions. 79, 213-224.
[5] Gawronová, M., Kielar, Š. & Lichý, P. (2022). Mulling and its effect on the properties of sand-water-bentonite moulding mixture. Archives of Foundry Engineering. 22(3), 107-112. DOI: 10.24425/afe.2022.140243.
[6] Multiserw-Morek. Catalogue of moulding and core mass testing equipment. Propagation catalogue. Retrieved January 20, 2023, from http://multiserw-morek.pl/!data/attachments/odlewnictwo_pl_a4_24str.pdf. (in Polish).
[7] Silica sand Biała Góra. Sand Team. Technical sheet. Holubice. Retrieved January 20, 2023 from: https://www.sandteam.cz/wp-content/uploads/2022/09/Biala_Gora_v6.pdf (in Czech).
[8] Keramost. Activated bentonite. Product Safety data sheet. Retrieved January 20, 2023 from: https://www.keramost.cz/dokumenty/sds-bentonite-activated-en.pdf.

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Authors and Affiliations

Š. Kielar
1
M. Bašistová
1
ORCID: ORCID
P. Lichy
1
ORCID: ORCID
  1. VSB - Technical University of Ostrava Faculty of Materials Science and Technology, Czech Republic

Technology of Production of Mold Filling Material for Specific Purposes in the Field of Metallic Foam Casting

I. Kroupová M. Bašistová P. Lichý V. Merta F. Radkovský J. Jezierski
Archives of Metallurgy and Materials | 2023 | vol. 68 | No 2 | 757-763 | DOI: 10.24425/amm.2023.142458
Keywords molding mixture metallic foams precursor abrasion loss 3-point bending strength
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Abstract

This paper describes the technology for the production of precursors (space holder material) used to form the complex internal structure of cast metal foam. The precursor material must exhibit sufficient refractoriness, resist contact with liquid metal and at the same time should exhibit good collapsibility after casting. With regard to the greening of foundry production, the focus of this paper was on materials that could exhibit the above properties and at the same time do not have a negative impact on the environment. In this paper, the technology for the production of spherical precursors from a self-hardening mixture with a geopolymer-based binder system is described and verified. The motivation for the choice of material and all the sub-steps of the process – molding into the core box, tumbling, including the necessary accompanying tests of the mechanical properties of the core mixture being verified – are described.
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Authors and Affiliations

I. Kroupová
1
ORCID: ORCID
M. Bašistová
1
ORCID: ORCID
P. Lichý
1
ORCID: ORCID
V. Merta
1
ORCID: ORCID
F. Radkovský
1
ORCID: ORCID
J. Jezierski
2
ORCID: ORCID
  1. VŠB-Technical University of Ostrava, Faculty of Materials Science and Technology, Department of Metallurgical Technologies, 17. Listopadu 2172/15, Ostrava-Poruba, Czech Republic
  2. Silesian University of Technology, Faculty of Mechanical Engineering, Department of Foundry Engineering, 2 Towarowa Str., 744-100 Gliwice, Poland

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