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Abstract

The technology of high-pressure die-casting (HPDC) of aluminum alloys is one of the most used and most economical technology for mass production of castings. High-pressure die-casting technology is characterized by the production of complex, thin-walled and dimensionally accurate castings. An important role is placed on the effective reduction of costs in the production process, wherein the combination with the technology of high-pressure die-casting is the possibility of recycling using returnable material. The experimental part of the paper focuses on the analysis of a gradual increase of the returnable material amount in combination with a commercial purity alloy for the production of high-pressure die-castings. The returnable material consisted of the so-called foundry waste (defective castings, venting and gating systems, etc.). The first step of the experimental castings evaluation consisted of numerical simulations, performed to determine the points of the casting, where porosity occurs. In the next step, the evaluation of areal porosity and microstructural analysis was performed on experimental castings with different amounts of returnable material in the batch. The evaluation of the area porosity showed only a small effect of the increased amount of the returnable material in the batch, where the worst results were obtained by the casting of the alloy with 90% but also with 55% of the returnable material in the batch. The microstructure analysis showed that the increase in returnable material in the batch was visibly manifested only by a change in the morphology of the eutectic Si.
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Bibliography

[1] Ragan, E. (2007). Die casting of metals. Prešov, Slovakia. (in Slovak).
[2] Eperješi, Ľ., Malik, J., Eperješi Š. & Fecko D. (2013) Influence of returning material on porosity of die castings. Manufacturing Technology. 13(1), 36-39. DOI: 10.21062/ujep/x.2013/a/1213-2489/MT/13/1/36.
[3] Gaustad, G., Olivetti, E. A. & Kirchain, R. (2012). Improving aluminum recycling: A survey of sorting and impurity removal technologies. Resources Conservation and Recycling. 58, 79-87.
[4] Matejka, M., Bolibruchová, D. & Kuriš, M. (2021). Crystallization of the structural components of multiple remelted AlSi9Cu3 alloy. Archives of Foundry Engineering. 21(2), 41-45. DOI: 10.24425/afe.2021.136096.
[5] Bruna, M., Remišová, A. & Sládek, A. (2019). Effect of filter thickness on reoxidation and mechanical properties of aluminium alloy AlSi7Mg0.3. Archives of Metallurgy and Materials. 3, 1100-1106. DOI: 10.24425/amm.2019.129500.
[6] Bryksi Stunova, B. & Bryksi, V. (2016). Analysis of defects in castings cast by rheocasting method SEED. Archives of Foundry Engineering. 16(3), 15-18. DOI: 10.1515/afe-2016-0041.
[7] Podprocká, R. & Bolibruchová, D. (2017). Iron intermetallic phases in the alloy based on Al-Si-Mg by applying manganese. Archives of Foundry Engineering. 17(3), 217-221. DOI: 10.24425/afe.2020.133321.
[8] Martinec, D., Pastircak, R. & Kantorikova, E. (2020). Using of technology semisolid squeeze casting by different initial states of material. Archives of Foundry Engineering. 20(1), 117-121. DOI: 10.24425/afe.2020.131292.
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Authors and Affiliations

M. Matejka
1
ORCID: ORCID
D. Bolibruchová
1
ORCID: ORCID
R. Podprocká
2

  1. University of Zilina, Faculty of Mechanical Engineering, Department of Technological Engineering, Univerzitna 1, 010 26 Zilina, Slovak Republic
  2. Rosenberg-Slovakia s.r.o., Kováčska 38, 044 25 Medzev, Slovak Republic
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Abstract

A comprehensive understanding of melt quality is of paramount importance for the control and prediction of actual casting characteristics. Among many phenomenon that occur during the solidification of castings, there are four that control structure and consequently mechanical properties: chemical composition, liquid metal treatment, cooling rate and temperature gradient. The cooling rate and alloy composition are most important among them. This paper investigates the effect of the major alloying elements (silicon and copper) of AlSi-Cu alloys on the size of secondary dendrite arm spacing. It has been shown that both alloying elements have reasonable influence on the refinement of this solidification parameter

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Authors and Affiliations

M. Djurdjevič
M. Grzinčič
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Abstract

High-pressure die casting results in a high quality surface and good mechanical properties of castings. Under the effect of pressure, integral and solid castings are achieved without a large number of foundry defects. The correct and proper setting of technological parameters plays a very important role in minimizing casting defects. The aim of the presented article is to determine the optimum maximum piston velocity for a casting in the high-pressure casting process with two height variants, depending on their internal quality. It is because the internal quality of particular castings is important in terms of proper functionality in operations where the biggest problem is the porosity of the casting. The main cause of porosity formation is the decreasing solubility of gases (most often hydrogen) during the melt solidification. Solubility represents the maximum amount of gas that can dissolve in a metal under equilibrium conditions of temperature and pressure. Macroporosity and microporosity were determined from the sections of the surfaces in the determined zones of the castings. Here, the results was that the macroporosity decreased with increasing piston velocity. Ideal microstructure was evaluated at a piston velocity of 3 m/s for both types of castings. On the other hand, the increase in tube size has shown that velocities of 3 m/s and higher, the tube is more prone to macroporosity formation. The highest hardness was achieved at the piston velocity of 2 m/s at both tube lengths.
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Authors and Affiliations

M. Matejka
1
ORCID: ORCID
D. Bolibruchová
1
ORCID: ORCID
R. Podprocká
2

  1. University of Zilina, Faculty of Mechanical Engineering, Department of Technological Engineering, Slovak Republic
  2. Rosenberg-Slovakia s.r.o., Slovak Republic

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