Improvement on Test Piece Mould Design for High Pressure Die Casting

Tan, Ger Lian (2021) Improvement on Test Piece Mould Design for High Pressure Die Casting. Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

High pressure die casting (HPDC) most common defect is gas porosity. This research aims to reduce this casting defect. The unique physical properties of Magnesium (Mg) alloy: lightweight, sustainable and low thermal conductivity had growing market potential. However, the research on this metal was lacking. This research has taken fluid turbulent kinetic energy as the cause of gas porosity formation. The existing factory’s mould (Sample Mould Design) was investigated with Mg alloy molten metal. Numerical simulations were done to analyze the thermal fluidic characteristic of the conventional and the two proposed design, Double Path (DP) and Outward Curvature (OC) Mould Design. Experimental shots for conventional mould were inspected by X-ray Computed Tomography Scan to identify internal gas porosity location. It was found that irregular fluid pattern and high turbulent kinetic energy had cause the formation of gas porosity. The uneven distribution of molten temperature had affected the die mould to experience thermal shock. This will cause the mould resulting in short die lifespan. The proposed designs had reduced the turbulent kinetic energy by 95.45% (DP) and 42.53% (OC). The total temperature was also reduced by 4.36% (DP) and 2.72% (OC). Comparison of porosity defect for numerical and experimental result had shown 12.04% deviation in porosity area. It was assumed that the cause of error came from machine, workplace environment error and the atomization of Mg alloy. The lack of previous research in molten metal properties had affect the value differences. A few preferable numerical software such as Catia and ProCAST are recommended. DP Mould had the best design but complex manufacturability, OC Mould had the next best and simpler design. Each design was considered novelty that could reduce gas porosity in HPDC. Keywords: High pressure die casting, mould design, numerical simulation, experimental

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