In the process of casting, there are many factors that affect the heat transfer coefficient of the casting mold interface:
(1) Parameters related to casting properties, such as casting geometry, casting material, pouring temperature and solidification direction, etc. The heat transfer coefficient of casting die interface of Al Si Cu alloy was studied by muojekwu et al. It is found that the values of heat flux and heat transfer coefficient of the casting die interface decrease with the increase of Si content, while other process conditions remain unchanged. They proposed that under the same superheating condition, with the decrease of Si content in the alloy, the thermal diffusivity and pouring temperature of the alloy will increase, so the value of interfacial heat transfer coefficient will also increase. This conclusion is consistent with the research results of Spinelli and hamasaiid. For the influence of metal pouring temperature on the heat transfer coefficient of casting die interface, muojekwu and Coates found that with the increase of pouring temperature, the heat transfer coefficient of casting die interface is also increasing. Ho et al. Studied the interfacial heat transfer behavior of pure aluminum and Al Cu alloy castings through experiments, and investigated the variation of the heat transfer coefficient of the casting mold interface when the castings are located at different positions above and below the mold. Griffiths et al. Also conducted a systematic study on how the solidification orientation affects the heat transfer behavior of the casting mold interface. It was found that the heat transfer coefficient of the casting mold interface is significantly higher when the casting is located above the mold than when the casting is located below the mold.
(2) Parameters related to mold properties, such as mold surface roughness, mold material and mold preheating temperature, etc. Muojekwu and others studied the influence of mold materials on the heat transfer coefficient of the casting mold interface through experiments. It was found that the heat transfer coefficient of the casting mold interface increased with the increase of the thermal diffusivity of the mold. The surface roughness of the mold is also an important factor affecting the heat transfer coefficient of the casting mold interface. Coates and others systematically studied the effect of mold surface roughness on the heat transfer coefficient of casting mold interface using pure aluminum as casting material. It was found that the heat transfer coefficient of casting mold interface increased with the decrease of mold surface roughness. Broucaret et al. Also studied the interfacial heat transfer behavior of pure aluminum castings. It was found that the decrease of initial mold temperature gradually accelerated the heat transfer between castings and molds, that is, the heat flux gradually increased. Santos and others systematically studied the influence of mold (or chilling layer) thickness on the interface heat transfer coefficient. It was found that the interface heat transfer coefficient increased with the decrease of mold thickness.
(3) The influencing factors related to the casting process include the coating used in the casting process (coating material and thickness) and the external pressure applied in the casting process (including pure external force and pressure due to hydrostatic head), etc. In metal mold casting, coating is very important. Therefore, the influence of coating (coating material and thickness) on the interfacial heat transfer coefficient has been widely concerned by researchers. It is found that the interfacial heat transfer coefficient increases gradually with the enhancement of the heat conduction performance of the coating. At the same time, with the increase of coating thickness, the interfacial heat transfer coefficient will gradually decrease. Hamassiid et al. Established the fitting relationship between the peak value of heat flux and heat transfer coefficient of casting die interface and coating thickness through a large number of experiments. It is found that when the coating thickness is thin, the peak value of the interfacial heat transfer coefficient will decrease rapidly with the increasing of the coating thickness. When the coating thickness exceeds a certain value, the decreasing trend of the peak value of the interfacial heat transfer coefficient will gradually slow down with the increasing of the coating thickness.
Compared with squeeze casting, there is no pressure or little pressure on the interface, which has little effect on the interface heat transfer. However, the methods of solving the interface heat transfer coefficient, measuring the internal temperature of the mold and analyzing the influence of different factors on the interface heat transfer are still valuable for the research of squeeze casting It is of great significance.
