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Evaluation of Collapsibility of Selected Core Systems

T. Obzina V. Merta J. Rygel P. Lichý K. Drobíková

Archives of Foundry Engineering | 2022 | vol. 22 | No 1 | 48-52 | DOI: 10.24425/afe.2022.140216

Keywords Foundry Foundry cores De-coring Knocking-out Collapsibility

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Abstract

There are mainly two different ways of producing sand cores in the industry. The most used is the shooting moulding process. A mixture of sand and binder is injected by compressed air into a cavity (core), where it is then thermally or chemically cured. Another relatively new method of manufacturing cores is the use of 3D printing. The principle is based on the method of local curing of the sand bed. The ability to destroy sand cores after casting can be evaluated by means of tests that are carried out directly on the test core. In most cases, the core is thermally degraded and the mechanical properties before and after thermal exposure are measured. Another possible way to determine the collapsibility of core mixtures can be performed on test castings, where a specific casting is designed for different binder systems. The residual strength is measured by subsequent shake-out or knock-out tests. In this paper, attention will be paid to the collapsibility of core mixtures in aluminium castings.

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Bibliography

[1] Dietert, H.W. (1950). Core knock-out, in Foundry Core Practice, 2nd ed. Chicago: American Foundrymen’s Society.
[2] Jorstad, J.L. (2008). Expendable-mold casting processes with permanent patterns, in ASM Handbook Vol. 15 Casting, 10th ed. ASM International
[3] Almaghariz, E.S., Conner, B.P., Lenner, L., Gullapalli, R., Manogharan, G.P. (2016). Quantifying the role of part design complexity in using 3D sand printing for molds and cores. International Journal of Metalcasting. 10, 240-252. DOI: 10.1007/s40962-016-0027-5.
[4] Vykoukal, M., Burian, A., Přerovská, M., Bajer, T., Beňo, J. (2019). Gas evolution of GEOPOL® W sand mixture and comparison with organic binders. Archives of Foundry Engineering. 19(2), 49-54.
[5] Steinhäuser, T. (2017). Inorganic binders-Benefits, State of the art, Actual use. In World Cast in Africa, Innovative for Sustainability, Proceedings of the South African Metal Casting Conference, Johannesburg, South Africa, 13–17 March 2017; WFO: Johannesburg, South Africa, p. 26
[6] Ramrattan, S. (2019). Evaluating a ceramic resin-coated sand for aluminum and iron castings. International Journal of Metalcasting. 13(3), 519-527. DOI: https://doi.org/10.1007/s40962-018-0269-5
[7] Ettemeyer, F., Schweinefuß, M., Lechner, P., Stahl, J., Greß, T., Kaindl, J., Durach, L., Volk, W. & Günther, D. (2021). Characterisation of the decoring behaviour of inorganically bound cast-in sand cores for light metal casting. Journal of Materials Processing Technology. 296, 117201, ISSN 0924-0136. DOI: https://doi.org/10.1016/j.jmatprotec.2021. 117201.
[8] Dobosz, P., Jelínek, K., Major-Gabryś, K. (2011). Development tendencies of moulding and core sands. China Foundry. 8, 438-446.

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Authors and Affiliations

T. Obzina

V. Merta

e-mail:

ORCID:

J. Rygel

P. Lichý

e-mail:

ORCID:

K. Drobíková

VSB - Technical University of Ostrava, Czech Republic

Investigations Concerning Improvements of the Knock Out Property of Ceramic Moulds Applied in the Investment Casting Technology

Joanna Kolczyk-Tylka Jerzy Zych

Archives of Foundry Engineering | 2023 | vol. 23 | No 4 | 34-39 | DOI: 10.24425/afe.2023.146676

Keywords Ceramic moulds Lost wax technology Knock-out properties Colloidal silica Wax model

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Abstract

In lost wax technology, self-supporting ceramic moulds are made, which must have adequate strength after being filled with liquid metal. The final structural strength is determined by such factors as the thickness of the individual layers applied to the wax model resulting from the viscosity of the liquid mass, the specific strength of the layers formed, and the heat treatment of the moulds. The development of technology and materials is moving in the direction of increasing the specific strength of self-supporting ceramic moulds. The consequence of this is that the final strength of these moulds is too high, making it difficult to knock castings out of the moulds. Removing mould remnants from holes, closed spaces of the casting, corners, sharp edges, variable cross sections and etc. is cumbersome. In order to remove mould remnants from the casting, a method is used to dissolve them in heated solutions of suitable chemical composition and reaction. The paper presents the results of research on a new solution, the essence of which is the production of layers in a ceramic mould, in the middle zone of the mould, characterized by a significantly reduced final strength, achieved after firing. These layers are produced using a different liquid ceramic mass than the base one, based on an organic binder. As a result, thanks to the embedded layer, very good knock-out of castings is achieved and separation of residual ceramic mass. Special layers can be incorporated over the entire surface or only in those places where the bonding of the casting surface and ceramic mass occurs.

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Bibliography

[1] Małek, M. Wiśniewski, P., Matysiak, H., Ziwlinska, M. & Kurzydkowski, K. J. (2013). Yttrium (III) oxide application for manufacturing prime coat of ceramic shell moulds used in investment casting. Glass Ceram. 6, 8-11. DOI: 10.13140/RG.2.1.1594.6002.
[2] Matysiak, H., Ferenc, J., Lipiński, Z., Grabarz, K., Michalski J., & Kurzydłowski, K.J. (2009). Characterization and monitoring of technological parameters of ceramic slurries used in the investment casting process of aircraft turbine elements using the Bridgman technique. Inżynieria Materiałowa. 30(4), 239-244.
[3] Wei-hua Liu, Xin Jia, Lai Song, & Ying-min Li. (2023). Effects of binder components and PVA modifier on bonding performance of phosphate binder for sand core-making. China Foundry. 20, 134-138. https://doi.org/10.1007/s41230-023-1021-1
[4] Pattnaik, S.R. (2017). An investigation on enhancing ceramic shell properties using naturally available additives. The International Jouranl of Advanced Manufacturing Technology. 91, 3061-3078. https://doi.org/10.1007/s00170-016-9975-4.
[5] Soroczyński, A., Haratym, R. & Biernacki, R. (2019). The role of recycled ceramic material obtained from the ceramic layered moulds used in the Investment Casting. Archives of Foundry Engineering. 19(1), 71-74. DOI: 10.24425/afe.2018.125194.
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[7] Karwiński, A. & Żółkiewicz, Z. (2014). The research of properties of experimental ceramic layers. Archives of Metallurgy and Materials. 59(2), 703-705. DOI:https://doi.org/10.2478/amm-2014-0115.
[8] Lu K, Liu X, Duan Z (2019). Effect of firing temperature and time on hybrid fiber-reinforced Shell for investment casting. International Journal of MetalCasting. 13, 666-673. https://doi.org/10.1007/s40962-018-0280-x.
[9] Kolczyk, J., Zych, J. & Jamrozowicz, Ł. (2017). Influence of the Al2O3 solid phase on the kinetics of binding ceramic moulds. Archives of Foundry Engineering. 17(4), 91-96. DOI: 10.1515/afe-2017-0136.
[10] Kolczyk, J., Zych, J. (2013). Kinetics of hardening and drying of ceramic moulds with the new generation binder – colloidal silica. Archives of Foundry Engineering. 13(4), 112-116. DOI: 10.2478/afe-2013-0093.
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Authors and Affiliations

Joanna Kolczyk-Tylka

e-mail:

ORCID:

Jerzy Zych

e-mail:

ORCID:

AGH University of Science and Technology, Faculty of Foundry Engineering, Krakow, Poland

Application of Liquid Glass Mixtures with Improved Knocking-Out Ability in Castings Production for Railway Transport

Y. Svinoroev K. Batyshev V. Deev K. Semenov V. Bykadorov E. Prusov

Archives of Foundry Engineering | 2019 | vol. 19 | No 3 | 27-32 | DOI: 10.24425/afe.2019.127134

Keywords Molds and cores Liquid glass mixtures Knocking-out ability Softening additives Steel casting

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Abstract

Analysis of the use of the Russian materials (liquid glass and softening additives) has been made in accordance with the modern requirements for use in the technological processes of casting as binding materials in the production of large-sized steel railway casting. The reasons for poor knockout of liquid glass mixtures have been investigated. A complex action softening additive has been recommended for a better knocking-out ability. This solution provides a softening effect at the points of maximum formation of the liquid glass matrix strength in the processes of polymorphic transformation of the material under the influence of elevated temperatures as the result of filling the mold cavity by the melt. It has been shown that the use of additives of complex action leads to the decrease in the specific work of the knockout by four – seven times depending on the composition of the mixture and the design features of the casting. Experimental-industrial tests of the proposed method for softening the liquid glass mixtures have been made and the "Front Buffer Stop" casting has been made (for the rolling stock of locomotives and railway wagons). The tests confirmed the effectiveness and expediency of implementation of new liquid glass mixtures with softening additives in conditions of foundry enterprises.

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Authors and Affiliations

Y. Svinoroev

K. Batyshev

V. Deev

K. Semenov

V. Bykadorov

E. Prusov

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Evaluation of Collapsibility of Selected Core Systems

Abstract

Bibliography

Authors and Affiliations

Investigations Concerning Improvements of the Knock Out Property of Ceramic Moulds Applied in the Investment Casting Technology

Abstract

Bibliography

Authors and Affiliations

Application of Liquid Glass Mixtures with Improved Knocking-Out Ability in Castings Production for Railway Transport

Abstract

Authors and Affiliations