Die casting is a metal casting process characterized by the application of high pressure to melted metal using an inner cavity of the mold. Molds are usually made from stronger alloys in a process similar to injection molding.
Most die casting castings are iron free, such as zinc, copper, aluminum, magnesium, lead, tin and lead-tin alloys and their alloys. Depending on the type of die casting, cold chamber die casting machine or hot chamber die casting machine is needed.
The cost of casting equipment and molds is high, so the die casting process is generally only used to manufacture large quantities of products in bulk.It is relatively easy to manufacture parts for die casting, which typically requires only four major steps with a low incremental cost per item.
Die casting is especially suitable for the manufacture of large quantities of small and medium-sized castings, so die casting is the most widely used of the various casting processes. Compared with other casting techniques, the surface of die casting is smoother and has higher dimensional consistency. Mainly used in zinc processing, can reduce the waste and increase the yield of direct injection process. Also by General Dynamics invention of precision and tight die casting technology and semi-solid die casting and other new die casting technology
The die casting mold is composed of two parts, respectively the covering part and the moving part, and the part combined with them is called the parting line. In hot chamber die casting, the covering part has a gate, while in cold chamber die casting, it is the injection port. The molten metal can enter the mold from here, and the shape of this part matches that of the injection nozzle in hot chamber die casting or the injection chamber in cold chamber die casting.
The moving part usually includes a push rod and a runner, which is the passage between the gate and the mold cavity through which molten metal enters the mold cavity. The covering part is usually attached to a fixed or front platen, while the movable part is attached to a movable platen. The cavity is divided into two cavity inserts, which are separate parts that can be relatively easily removed or installed from the mold by bolting.
The mold is specially designed so that the casting remains in the moving part when the mold is opened. In this way, the moving part of the push rod will push the casting out. The push rod is usually driven by the pressure plate, which will drive all the push rods at the same time with exactly the same amount of force, so that the casting is not damaged.
When the casting is pushed out, the platen contracts to pull all the pusher back, ready for the next die casting.Because THE CASTING IS STILL IN HIGH temperature when the mold is released, only a sufficient number of push rods can ensure that the average pressure on each push rod is small enough not to damage the casting. However, the push rod will still leave marks, so careful design MUST BE made so that the position of the push rod does not affect the operation of the casting too much.
Other parts in the mold include the core slide, etc. Cores are parts used to make holes or openings in the casting. They can also be used to add detail to the casting. There are three main types of cores: fixed, movable and loose. The orientation of the fixed cores is parallel to the direction in which the casting comes out of the die. They are either fixed or permanently attached to the die. The movable core can be arranged in any direction except the exit direction. Before opening the mold after solidification, the movable core must be removed from the mold cavity by means of a separation device. The slider and the movable core are very close, the biggest difference is that the slider can be used to create a concave surface. The use of cores and sliders in die casting can add substantially to the cost. 。 Loose cores are also called drop-outs and can be used to make complex surfaces, such as threaded holes. 。 Before the start of each cycle, the slider needs to be manually installed and finally pushed out with the casting. Then take out the loose core. 。 Loose core is the most expensive core because it is labor intensive to manufacture and it increases cycle time.
