ABSTRACT
A die casting process has been widely used in the manufacturing of automotive parts which require near-net shape casting and high productive rates. However, high-pressure die castings usually contain regions of gas porosity due mainly to the entrapment of air or gas in the die during the high-speed injection of molten metal into the die cavity. Gas porosity in castings has hampered the wider use of this method in the creation of high-durability automotive components. However, to establish a shot condition in the shot sleeve during the die casting process is critical, and difficulty remains when attempting to optimize the shot condition to avoid air entrapment effectively. In this study, ADC12 plate die castings were fabricated under various shot conditions, in which different plunger velocities and fast shot set points. In addition, according to the shot conditions, die casting experimental results were compared with an experiment involving a water model and with the results of a numerical analysis. The porosity of the castings was analyzed using CT and using density and microstructural analyses, and the effect of the porosity on the mechanical properties was analyzed using hardness and tensile testing. When the plunger velocity was 1.0 m/s and the fast shot set point is cavity 0, 25% position, the results with the castings were optimal, with good mechanical properties and few areas of porosity. In addition, the simulation results were mostly in agreement with die-casting experimental results.(Received March 18, 2015)
keyword : alloy, casting, mechanical property, image analysis, simulation, porosity
