How to Choos Die CastingType?
The die casting process can be typically divided into two different types: Cold Chamber Die Casting and Hot Chamber Die Casting.
Cold Chamber Die Casting is the process primarliy for manufacturing of aluminum die castings. In cold chamber die casting, it uses a ladle to transport the molten metal from the holding furnace into the unheated shot chamber or injection cylinder. This metal is then shot into the die by using a hydraulic piston. The main disadvantage of this process is that it is relatively slower compared to the hot chamber die casting process.
Hot Chamber Die Casting is the process mainly for alloys like zinc, magnesium or copper. In hot chamber die casting, the injection system is immersed in pool of molten metal hence the name. The furnace is attached to the machine via a feeding system called a gooseneck. As the cycle begins the piston will retracts, which allows the molten metal to fill the “gooseneck” from a port in the injection cylinder. As the plunger move downwards, it seals the port and forces the molten metal through the gooseneck and nozzle into the die. Once the metal solidifies, the plunger will pull upwards. Afterwards, the die will open and the part is ejected. The advantage of this process is its short cycle time and it does not require metal to be transported from a separate furnace. Unfortunately, this die casting process is only suitable for alloys that do not attack the injection cylinder.
Advantages of Die Casting
Durability–Compared to plastic parts, die castings are stronger than their plastic counterparts. In most cases, even if thinner parts, die casting can still maintaining its strength for its application. Furthermore, die cast parts are able to withstand to a wide range of temperature, making it workable in harsh temperatures and working environments.
High production effeciency–Due to the ability to produce complex parts in net shape with little or no machining processes required, it will greatly reduce the production time. So die casting is considered as one of the most effective process to mass produce non-ferrous metal complex parts.
Freedom of size–With die casting process, we are able to parts with a wide range of shape and sizes. Unlike other manufacturing processes such as forging, the die casting process does not limit the shape of parts and in most cases will be the net shape of the parts.
Green Manufacturing–How long does it takes for plastic to biodegrade? According to scientists, plastics takes at least a few hundreds of years to degrade fully. This means that obsolete plastic products are pilled up in the landfills, polluting our beaches, killing millions of sea animals and causing health hazards to the inhabitants in our neighborhoods. Unlike plastic, die casting parts are primarily made of recycled material. On average, approximately 95% of the metal is recycled from salvaged parts, making it a sustainable material that can be used over and over again without degradation. So die casting is a green manufacturing technique.
Casting with inserts–The die casting process allows inserts to be cast-in to form certain features such as threaded inserts, heating elements or high strength bearing surfaces.
Thinner Wall Castings–Compared with sand casting or gravity die casting, due to the high pressure during the injection process, die casting is able to produce parts with thinner wall thickness. This allows lightweight construction as well as eliminate or reduce the need of secondary operations.
Disadvantages of Die Casting
The main disadvantage to die casting is the very high production cost. Compared to other casting process, both the casting equipments required and the dies and related components are all costly. Therefore, to make die casting cost-effective, a large production volume is preferred. Other disadvantages are that the process is limited to high-fluidity metals, and casting weights must be between 30 grams and 10kg. In the standard die casting process the final casting may have a small amount of porosity. This prevents any heat treating or welding, because the heat causes the gas in the pores to expand, which causes micro-cracks inside the part and exfoliation of the surface. Thus a related disadvantage of die casting is that it is only for parts in which softness is acceptable. Parts needing hardening (through hardening or case hardening) and tempering are not feasible for die casting.
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