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What Is Die Casting and How Does It Work

  • Die casting is one of the most important metalworking processes, and it ranks high on the list of important metalworking processes. Die casting is similar to other types of casting in that molten metal is poured into a two-piece mold, but the material is forced into every nook and cranny of the cavity within the mold under pressure. Because of this, die cast components are typically extremely accurate. Even when dealing with complex geometries, the technology is capable of producing net or nearly net shapes, as well as smooth surfaces on top of that. In turn, this means that only minimal secondary machining is required, further lowering costs. Furthermore, because the process is relatively quick compared to traditional casting methods, it is a favorite of high-volume manufacturers such as automobile manufacturers and companies that manufacture consumer products.

    Die cast models of the Matchbox cars and Monopoly game pieces that you may remember from your childhood are available. Most engine blocks, transmission housings, cylinder heads, and alternator bodies are also made of aluminum. Apart from plumbing components and laptop computer frames, die cast components are used in the manufacture of toaster and blender bases, and they are also used in the manufacture of components for the medical, communication, electrical, and firearm industries, among other things. Die cast components can be found everywhere.

    Although copper and bronze can also be die cast, the majority of die cast parts are made of "white metals" such as zinc, aluminum, or magnesium, although copper and bronze are also available. On the other hand, ferrous materials such as iron and steel are found in traditional mold-based casting processes, such as custom die casting. It is preferred that white metals be used for their low melting points, corrosion resistance, and high strength to weight ratios, which make them ideal for applications where light weight is an important consideration.

    DO YOU PREFER IT HOT OR COLD?

    Die casting is primarily divided into two types that are currently in use. A hot chamber die casting machine, as the name implies, is comprised of a heated chamber filled with molten metal, within which is housed a cylinder and piston mechanism that produces the die casting. At the start of the casting process, the piston retracts, allowing metal to fill the cylinder through a port that has been opened by the piston. After that, the "shot" is forced through a valve and into the cavity of the die. As soon as the metal has solidified enough to allow the die halves to separate, the part is removed and the entire process is repeated once more. Due to the lower melting points of zinc and magnesium, hot chamber alloy die casting company is the method of choice for producing these metals.

    Machines that use cold chamber , on the other hand, fill the cylinder with molten material through the use of a ladle. While this additional step makes cold chamber die cast parts more time-consuming than hot chamber die casting, it allows for the casting of aluminum and other metals with higher melting temperatures because the injection mechanism is not constantly immersed in extremely hot liquid metal as in hot chamber die casting. As well as standard die casting, there are a variety of variants and proprietary systems available, such as low-pressure and vacuum molds, squeeze molds, and die casting using multiple slides for parts with high complexity.

    ABOVE AND BEYOND THE DIE

    There are several caveats to . As a starting point, secondary operations are usually required to finish die cast parts after they have been poured. Drilling and tapping holes, as well as milling or turning critical surfaces, are required. Belt sanding may be required to "deflash" die cast parts; however, depending on the complexity and quantity of the parts, a trim die may be used to shear away any excess material in a single operation, saving time and money. Vibratory deburring, also known as rotary tumbling, is also common for smaller parts, and it is useful for smoothing out sharp edges. The latter, on the other hand, is frequently unnecessary because the surface quality of most die cast parts is excellent. And, like virtually any metal part, die cast components can be treated with plating, painting, anodizing, or coating to improve their corrosion resistance or to make them more aesthetically pleasing.

    Take note of the term "deflash" that was just mentioned. In the previous section, we learned that the die, also known as a mold, is a two-part tool that contains runners and sprues through which the molten material is forced to flow during the casting process. When the casting cycle is completed, the die's movable half retracts, and ejector pins contained within the die force the finished part and its attached runners out of the die and into the casting chamber. A trim die or even a hand tool can be used to cut away the runners before using an abrasive belt to smooth out the rough edges.

    Even when subjected to the intense pressures of the die casting process, even the most precisely machined die surfaces can allow a small amount of material to escape between the two when subjected to the flashing. These are referred to as parting lines. In both die casting and plastic injection molding, the same phenomena can be observed; however, just as with die casting, all of these can be minimized through the use of a well-designed, high-quality die and the proper application of casting parameters such as metal temperature, pressure, and flow. Parting lines are common, regardless of the process, and must be removed mechanically if aesthetics are a consideration.