What Is Die Casting

Die casting process is a process that unifies pressure, speed and time by using three elements, such as machine, mould and alloy. The presence of pressure is a major feature of the die casting process that distinguishes other casting methods.

Die casting is a kind of special casting method with less cutting and less development in modern metal processing technology. It is a process of filling a molten metal at a high pressure and high speed and crystallizing it under high pressure to form a casting. High pressure and high speed are the main features of pressure casting. The commonly used pressure is tens of megapascals, the filling speed (inner gate speed) is about 16 to 80 m/sec, and the time for the molten metal to fill the mold cavity is extremely short, about 0.01 to 0.2 seconds.

In 1964, the Japan Die Casting Association defined die casting as "a method of casting a molten alloy into a precision mold at a high temperature and producing a high-precision casting with excellent casting surface in a short time." In the United States, die casting is called die casting, and in the UK, die casting is called pressure die casting. Castings produced by die casting are called die castings.

Molds are usually machined from higher strength alloys, some of which are similar to injection molding. Most die castings are iron-free, such as zinc, copper, aluminum, magnesium, lead, tin, and lead-tin alloys, as well as alloys thereof. Depending on the type of die casting, a cold chamber die casting machine or a hot chamber die casting machine is required.

Casting equipment and molds are expensive, so the die casting process is generally only used to mass produce a large number of products. It is relatively easy to manufacture die-cast parts, which generally requires only four major steps, with a single cost increment being low. Die casting is particularly suitable for the manufacture of a large number of small and medium-sized castings, so die casting is the most widely used of various casting processes.

Compared with other casting technologies, die casting has high production efficiency, simple process, high tolerance of castings, good surface roughness and high mechanical strength, which can save a lot of mechanical processing steps and equipment, and save raw materials. It has become an important part of the foundry industry in different countries.

The process of filling the cavity by the metal during die casting is a process of unifying the process factors such as pressure, speed, temperature and time. At the same time, these technological factors interact with each other, restrict each other, and complement each other. Only by properly selecting and adjusting these factors and making them consistent can we achieve the desired results.

Therefore, in the die casting process, not only the processability of the casting structure, the advancement of the die-casting mold, the performance and structural superiority of the die-casting machine, the adaptability of the die-casting alloy and the standardization of the smelting process, but also the pressure, temperature and time should be emphasized. These process parameters have very important effect on the quality of castings. Effective control of these parameters should be emphasized during the die casting process.