This thesis describes optimization of die temperature in high pressure die-casting (HPDC) of A380 alloy by experimental observation and numerical simulation with the use of statistical tools. The goal of this research is to determine the optimum die temperature to minimize incidence of these defects and thus maximize production of parts without defects.
In HPDC, molten metal is injected into the die at high speed (40-60 m/s for aluminum alloys). Die temperature plays an important role on the rate of rejected parts. Therefore, flow patterns of molten metal in HPDC of an automotive component with very complex geometry (the ladder frame from the EF7 motor) were examined to determine the optimal die temperature.
Defects in the production process fall into three categories, including surface, internal and dimensional defects. Samples produced in the experiments were classified according to any present defects.
Another important parameter that influences casting defects is the cooling rate. Die temperatures were measured at the initial step and final filling positions. Experiments were performed with die temperatures ranging from 150 °C to 250 °C. The results show that the melt temperature difference in the die between the initial step and the final filling position was between 20 and 25 °C.
Statistical tools such as regressions, relationships, max, min, correlations, ANOVA, T-test, Principal Component Analysis (PCA) and descriptive statistics were used to facilitate interpretation of data from the die-cast experiments.
Perform some case studies in order to study the process behavior, take a better knowledge of effective parameters, and measure the required parameters. The collected data are utilized to:
- Set the model
- Validate/ verify the model
ProCast software was used to simulate the fluid flow and solidification step, and the results were verified by experimental measurements. The optimal die temperature for this alloy was found to be above 200 oC.
Statistical analysis of the experimental results found that defects were minimized and confirmed parts were maximized in HPDC of the ladder frame within a die temperature range of 210° C to 215° C.
Västerås: Mälardalen University , 2015.