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Role of Metal Quality and Porosity Formation in Low Pressure Die Casting of A356: Experimental Observations

Gursoy O., Nordmak A., Syversten F., Colak M., Tur K., Dispinar D.

Archives of Foundry Engineering

2021

Vol. 21, iss. 1

5--10

Porosity is one of the major problems in casting operations and there are several discussions in the literature about the porosity formation in aluminum castings. Bifilms are the defects that are introduced into the melt by turbulence. They can be detected with reduced pressure test and presented numerically by measuring bifilm index. The measure of bifilm index is the sum of total oxide length given in millimeters from the cross-section of reduced pressure test sample solidified under 0.01 MPa. In this work, low pressure die casting (LPDC) unit was built in an attempt to enhance the producibility rate. The unit consists of a pump housing that was placed inside the melt in the melting furnace where the pressure was applied instead of the whole melt surface. It was observed that the melt quality of A356 alloy was deteriorated over time which had led to higher porosity. This was attributed to the increased oxide thickness of the bifilm by the consumption of air in between the folded oxides. A relationship was found between bifilm index and pore formation.

The effect of filter type on filling during Low Pressure Die Casting: a numerical study

Yavuz H., Kara A., Çubuklusu H. E., Çe Ö. B., Aybarç U.

Journal of Achievements in Materials and Manufacturing Engineering

2016

Vol. 75, nr 2

71--77

Purpose: Effect of filter types on filling during low pressure die casting researched to find optimal filtration design for wheel casting process. Design/methodology/approach: Three types of filters, which are commonly used during low pressure die casting for light alloy aluminium wheel production, investigated with numerical simulation. In addition, numerical simulation for without filter is made for control variable. According to numerical simulation results, filling time, molten metal velocity results are used to define suitability of the molten metal for wheel casting. Thirteen Control points and two filtration areas generated to calculate the molten metal velocities before and after the filtration areas. Findings: Three different filtration designs for aluminium wheel casting compared according to molten aluminium velocity results of numerical simulation in terms of flow of melt. Filtration design with flat filter is the optimal filtration design for aluminium wheels casting, according to numerical simulations. In addition, combination of other filters with flat filter is suggested to find optimal filtration design according to performance of filters during low pressure die casting. Research limitations/implications: 0.5 m/s velocity for molten metal is accepted as a critical maximum limit for reliable casting according to literature search on aluminium casting. No field test was done in this study. Originality/value: Effect of flow properties on casting quality is promising research field and the effect of filters is part of this research field.