Die casting machines provide an efficient way to mass-produce a wide variety of accurately dimensioned, sharply defined, smooth, or textured-surface engineered metal parts. There are different types of die casting machines but almost all of them use high pressure to force molten metal into a mold or die. After the metals cools and hardens the part is done. This process is sometimes viewed as the shortest process from raw material to the final product. Most of the time die casting machines are used to process non-ferrous metals such as zinc, aluminum, lead, copper, or tin to make die-cast parts.
Generally speaking, we can distinguish between hot-chamber and cold-chamber die casting machines. Both types have their pros and cons and specific types of dies or molds require one or the other. Metals with a high melting point need to be processed with cold chamber die casting machines. The high temperatures required for metals such as aluminum, magnesium and copper to achieve a molten state means that a separate furnace must be used, which is why some manufacturers choose cold chamber die casting rather than hot chamber die casting.
Large or small die casting machines both inject molten metal into a mold, however the type of injection various depending on the size of the machine. Let’s talk about both types of die casting machines one after the other.
Hot chamber die casting machines
Hot chamber die casting machines are also called gooseneck machines in the industry. The most unique feature of this type is that the metal is melt directly inside the machine. There is no external machine or furnace necessary for the production process. These use hydraulic pistons to drive molten metal out of the furnace and into the mold. The process of creating a part with hot chamber die casting machines is very fast. Standard parts take only 15 – 20 minutes to be ready.
Cold chamber die casting machine
If you only look at the name, you might assume that cold chamber die casting is about directly forcing cold metal through the cavity of the mold without heating it up beforehand. However with cold chamber you still need to press molten metal into the mold, it is virtually impossible to do that without heating it up. The difference compared to hot chamber die casting is that with the cold chamber die casting method this step is performed in a separate furnace. Afterwards the part is moved to the die casting equipment. For cold chamber die casting, the metal is first heated in a separate furnace to reach the molten state. The molten metal is then transported to the casting machine and then sent to the casting chamber. The machine uses a pressurized plunger to press the molten metal into the cavity of the mold. Cold chambers and cold chamber casting machines can be further divided into subcategories. Some of the more specialized die casting machines used in certain applications include semi-solid forming machines for manufacturing semi-solid metals and squeeze casting machines, which are alternative methods for manufacturing low-porosity, heat-treatable components to reduce entrained gas.
Tonnage of the clamping force are the two most important specifications of hot chamber die casting machines and cold chamber die casting machines. The required clamping force depends on the projected area of the parts in the mold and the pressure of the molten metal injection. Consequently you need a larger clamping force for bigger arts. Besides, some materials neeed to be processed at a higher pressure and therefore require higher tonnages. Maximum injection volume, the clamping stroke, minimum mold thickness are also important parameters that define what kind of parts and what dimension the machine can support. The size of die castings may vary greatly, so these measures need to be taken to cover a large range.
Although most die-casting machines have automation capabilities, more advanced (and more expensive) machines can automate almost all steps in the casting process, including mold lubrication, dressing, quenching, and casting in cold chamber casting. If used in conjunction with processing equipment based on hydraulic or metal speed analysis and adjustment of the casting process, automation may also reduce the level of manual quality control.
Die casts are obviously the most crucial part of a die casting equipment. The four most common types are single-cavity, multi-cavity, unit and combination dies. Single-cavity dies are good for creating solid components that consist of one body. Multi-cavity dies are more flexible and allow for the production of multiple parts of the same kind. Unit dies also create multiple parts simultaneously, but different ones. And finally, combination dies are best at casting many unique components for future assembly.
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