Experimental and theoretical investigation of heat transfer in vacuum assisted high pressure die casting (HPDC) process

In the HPDC, the determination of the IHTC is important for improving the part quality. This value varies due to factors like casting temperature, mold temperature, injection pressure, velocity, roughness, design, and alloy type. This study focused on A384 alloy, using both experimental and numerical methods to determine IHTC and heat flux values during high-pressure die casting under different injection conditions. Temperature data from 18 thermocouples on the mold and casting part were recorded, and interface heat transfer coefficient and heat flux were calculated using a C# program and finite difference method (FDM). Experiments were conducted with varying injection pressure (80 – 160 bar), injection velocity (1.5 – 2.5 m/s), mold temperature (373 – 453 – 533 K), and casting temperature (973 – 1033 K), totaling 48 combinations. ANSYS Fluent modeled the casting process, and numerical analysis mirrored experimental parameters, presenting results graphically. Thus, numerical analysis were carried out using the same parameters as in the experimental studies, and the results of the heat transfer coefficient and heat flux values were presented as time-dependent graphs. As a result of the studies, it has been observed that increasing the injection pressure, injection phase velocity, and casting temperature lead to an increase in both the Heat Transfer Coefficient (IHTC) value and the heat flux. However, an increase in the mold temperature has resulted in a decrease in these values. Furthermore, through conducted experimental research, it has been demonstrated that the application of vacuum enhances both the IHTC and heat flux values.