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S. Kastelic1,3, M. Grah2 , J. Seljak2 , D. Kogoj2 , A. Mahmutović3 , P. Mrvar1
1University of Ljubljana, Faculty of Natural Sciences and Engineering, 2ETA d.o.o. Cerkno, 3TC Livarstvo d.o.o., Slovenia
NUMERICAL CALCULATION CALIBRATION FOR OPTIMIZATION OF FOUNDRY TECHNOLOGY OF A HEAT PLATE
Abstract
Numerical calculations in the designing and optimization of foundry technologies can contribute significantly to help understand a problem that is not apparent at first glance. Numerical calculation of the foundry process is now able to show us in detail every sequence of the process so that we can discover and understand the root cause of the problem. With an understanding of the root cause of the failure, we can effectively optimize the process. The new technology can then be virtually tested by numerical calculation using new optimized boundary conditions. In this way, we can significantly reduce the time and cost of developing a new process or optimizing an existing technology.
Confidence in the accuracy of the results of the numerical calculation depends on the self-criticism of the user who analyses the results. The accuracy of the numerical calculation can be as good as the initial and boundary conditions are accurate. The accuracy of the results also depends on the material properties in the database – the alloys used and the properties of other foundry materials. For some of the input parameters, there are only recommended values that need to be calibrated for a particular technology and a particular technology in a particular foundry.
In this presentation, the calibration of the heat transfer coefficient at the boundary between sand mold and casting is presented. The calibration was performed by measuring the temperatures in the sand mold at several points during casting, solidification, and cooling of the casting. The measured temperatures were then compared to the calculated temperatures. The heat transfer coefficient was calibrated so that the calculated temperatures matched the measured temperatures. The process of calibrating the heat transfer coefficient was performed together with the optimization of the gating system of a heat plate to eliminate porosity in the casting.
Keywords: gravity casting, gray iron, heat transfer coefficient calibration, casting technology optimization
2.
D. Molnár
University of Miskolc, Hungary
REVERSE ENGINEERING OF ARTEFACTS
Abstract
In this paper, the casting technology and casting defects of a socketed axe artifact were examined using computer simulation and non-destructive materials characterization methods.
The spread of cast bronze axes in the Carpathian Basin started in the Early Bronze Age. Bronze axes can be found in the highest number and selection in the local findings from the Late Bronze Age (1500-900 B.C.). There are several types of developed axe geometries, while the most common types are the so-called socketed axes, which can be found in ritual bronze treasures, scattered findings, and sometimes as grave annexes. The examined socketed axe artifact (Hungarian National Museum, Prehistoric Collection) was physically analysed. The chemical composition was analysed by promptgamma activation analysis, which is a nuclear analytical technique for the non-destructive determination of elemental and isotopic compositions. The outer shape and the inner structure of the socketed axe artifact were examined by neutron radiography.
Based on the artifact an experimental casting replica and a virtual geometry were created for detailed investigations. The reason for the construction of the virtual geometry is that the examination possibilities of the original artifact are limited, only non-destructive methods can be applied. The experimental casting replica is less limited to examination methods, but because of the casting defects, the results can be less representative. On the other hand, virtual geometry is free to examine, several times can be cast virtually, and the possibilities of different testing methods are unlimited.
By the application of computer simulation, several filling and solidification cases were tested, and the effect of the mould material and melt temperature on the porosity distribution was examined. Casting phenomenon connected to the geometry (modulus), to the filling (gating system design, melt flow, movement of the melt inside the cavity, turbulence, air entrainment, and the position of air bubbles), and to the solidification (feeding mechanism, shrinkage formation and solidification time) were analysed.
The simulation results were validated by neutron radiography images and microstructure analysis using bright-field microscope analysis and differential interference contrast analysis.
Keywords: Casting, Bronze Age, socketed axe, computer simulation, reverse engineering artifact, reverse engineering, gravity casting technology, simulation
3.
R. Deike
University Duisburg-Essen, Germany
THE SPECIAL IMPORTANCE OF METALS IN A CIRCULAR ECONOMY
Abstract
When the 17 Sustainable Development Goals were adopted at the UN General Assembly in 2015 they were still formulated as a vision of how to achieve a better world with more prosperity and less resource consumption, we are now entering a time in which parts of this vision are beginning to become law. For example, the EU’s Circular Economy Action Plan brings the importance of sustainability and the development of sustainable processes into the focus of European policy. What is sustainable and what is not is to be described, classified, and specifically promoted, e.g. also through the management of financial flows. As important as the emphasis on sustainability and the promotion of appropriate ways to achieve it are, there are certain concerns if what is relatively easily described, legally defined, and then decided upon in the administrations of political institutions and companies in the financial industry is always technically feasible. After all, even a circular economy has scientific and technical limits that have to be accepted in terms of economic efficiency. However, sustainability must also be considered in the context of structural changes in national economies. Developments in the field of metals show that in the traditional industrial societies in Europe and Japan, structural changes from industrial to service societies have taken place, which have temporarily led very clearly in the global steel and foundry industry to the fact that the per capita consumption of steel and cast products in the period between 1970 and 1995 has no longer increased and in some cases, even the absolute consumption has decreased with a growing world population. Here, then, the dematerialization of global economic growth has already taken place in selected areas. With the industrialization in China, this development has ended, especially at the beginning of this century, and exponential growth with extreme raw material consumption and price increases has taken place again. However, this development will very likely end in the next two decades, namely when the structural change from an industrial to a service society will also take place in China.
Keywords: sustainable development, processes, legislation, European and world politics