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As a result of the applied pressure, the molten metal rises up an ascension pipe and fills the cavity of a binderless silica sand mold, which has a foam pattern filling the chamber of the mold.
High-pressure die casting (HPDC) is a very popular process for producing complicated mechanical parts out of light metals such as aluminum and magnesium alloys (aluminum vs magnesium die casting), and it is becoming increasingly widespread.
The new method - the low pressure lost foam casting technique for magnesium alloys - is a novel technology that combines the advantages of high gravity lost foam casting with the advantages of low - pressure casting to produce a product that is both lightweight and strong. As a result of the applied pressure, the molten metal rises up an ascension pipe and fills the cavity of a binderless silica sand mold, which has a foam pattern filling the chamber of the mold. When the foam pattern is vaporized by the casting heat, it is replaced by the molten metal, which fills the space left by the foam pattern. In order for the mold to be able to suck out the casting gases and stable the mold, it must be subjected to low pressure during the casting process.
When it comes to mold filling behavior, the primary difference between gravity casting and low-pressure lost foam casting is the fact that in gravity casting, the mold filling veiocity v = f (p), with p = f (h), and h = const., cannot be controlled but in low-pressure lost foam casting, it can. The mold filling speed can be controlled in low-pressure casting with p = f (t), but not in high-pressure casting. It is feasible to design a regime for the regulation of compressed air by mimicking the flow patterns that occur during low-pressure casting.
An illustration of the Low - pressure Lost Foam casting plant for magnesium alloys
The casting (cover pump) has a difficult geometry due to the way it was cast. Despite this, it was possible to cast it without difficulty utilizing the low-pressure lost foam technique and a magnesium-based alloy. The following parameters had been established: The casting temperature was 840°C, the pressure holding time was 90 seconds, and the pressure rising time was 8 seconds.
Using the low-pressure lost foam casting method, a magnesium casting (cover pump) was created (FIAT component).
High-pressure die casting (HPDC) is a very popular process for producing complicated mechanical parts out of light metals such as aluminum and magnesium alloys, and it is becoming increasingly widespread. Among the technologies used to manufacture parts composed of magnesium alloys, the high pressure die casting technique (HPDC) is the most widely used. The method is characterized by quick die filling, followed by rapid cooling and solidification of the metal in the die once the metal has been cooled and solidified. The mechanical qualities of magnesium die casting alloys are improved as a result of these characteristics, but a potential flaw, which is typically seen in high pressure die cast components, is porosity, which restricts the range of applications for magnesium alloys.
It is capable of produce parts in a short amount of time while maintaining excellent dimensional accuracy. HPDC expansion followed that of the automobile industry, where the needs of assembly line manufacturing sparked a demand for a quick and reliable means to manufacture component parts and assemblies. With the expansion of just-in-time manufacturing, the automobile sector has maintained its position as the primary user of HPDC parts. Recreational vehicles, power tools, electrical gear, electronic components, and housewares are just a few of the applications for die casting that exist.
Optimisation of the high vacuum die casting process for the production of magnesium alloys. High-vacuum die casting of magnesium alloys was explored, and a high-vacuum valve, as well as die sealing and vacuum layout technologies, were successfully created in order to maintain a cavity vacuum pressure of less than 5kPa during the die casting process.
Based on this mathematical model, the vacuum system's gas evacuation process was optimized and the vacuum system was successfully installed and operational. After further development, a high vacuum die casting process with a vacuum level of 5kPa and a vacuum building time of 1.5s can be accomplished for practical high vacuum die casting applications with a vacuum building time of 1.5s. By employing a step-shape die casting die along with a typical mechanical properties test die, it was possible to evaluate the mechanical properties and T6 heat treatment properties of AM50 magnesium alloy produced through a high vacuum die casting technique.
Simulation and modeling of the high pressure die casting process are carried out. In the horizontal cold chamber die casting process, air that becomes entrapped in the molten metal during the casting process has a significant impact on the production of porosity in the finished product. The results of the numerical simulation were consistent with the results of the water analogue experiment. A study was conducted based on numerical simulation findings to determine the effects of plunger acceleration and the slow shot speed scheme on the wave profile of the liquid metal in the shot sleeves under a variety of different fill ratios and sleeve diameters under various conditions. The use of optimal plunger acceleration and a slow shot speed strategy was recommended in order to reduce the amount of gas trapped in the shot sleeve.
In order to anticipate the gas porosity of die castings, a three-dimensional numerical approach was developed to predict the air entrapment defects in the high-pressure die casting (HPDC) process. Using the fluid flow model, the pressure of the isolated gas bubbles was taken into account using the ideal gas law and gas concentration transport equation, as well as the pressure of the isolated gas bubbles. When filling was completed, the concentration of air in the liquid metal reflected the distribution of entrapped air that had been trapped during the process. The mathematical model was verified by comparing the results of the simulation with the results of the X-ray inspection of die castings, which was carried out.
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