Die Casting Process
Die casting is the method used for forcing molten metal into mold cavities under high pressure. Die casting is very versatile and hence, is the widest used method for casting a metal. Die casting is same as permanent mold casting the only difference is that the metal is injected into the mould at very high pressure of 10-210 Mpa. This results in a more uniform part, usually good dimensional accuracy and also good surface finish.
The different metals and alloys that can be used in die casting are zinc die casting, aluminum casting, copper, magnesium die casting, tin and lead. Ferrous metals can also be used for die casting, die casting method is generally used for applications in which a large quantity is medium or small sized parts are required with detail, good dimension and fine surface finish.
There are namely two equipments used for die casting cold chamber and hot chamber process.
Cold Chamber process: In the cold chamber category of die casting, a cold chamber of each module is filled with molten metal. The time exposure provided for the molten metal to plunge the walls of the mold is less. This clod chamber process method is very useful for metals like aluminum, copper and metals that easily alloy with iron at high temperatures.
Hot Chamber process: In the hot chamber process method of die casting, the pressure that is connected to the die cavity is forever and permanently in molten metal. As the plunger moves towards the open position that is towards the non – pressurized area, the inlet port connected to the pressurizing cylinder is uncovered.
The die casting molds which are used in this method are expensive and take usually take long production time. These die casting modules are also called as “dies’
Advantages of Aluminum Die Casting: The method of die casting gives excellent dimensional accuracy. The dimensional accuracy is as good as 0.1mm for the first 2.5cms and 0.005 for the first inch. Die casting also provides with smooth cast surfaces. Small and thin walls and can be made using the method of die casting walls as tiny as 0.75mm approximately can be casted. Inserts like thread insert, high strength bearing surfaces and heating elements can also be inserted using the Die Casting method. Die casting also helps in reducing or even completely eliminating the use of secondary machining operations. The use of Die Casting method also helps to reduce the production time and a huge number of articles can be produced in a very short time. Die casting method also helps to retain as well as increase the tensile strength of the metal. It offers tensile strength as high as 415 MPa that is 60ksi.
Disadvantages of Aluminum Die Casting: The casting weight is very less hardly between 30 grams and 10 kgs. Also the size of the material that needs to be casted using the Die Casting method needs to small say around 600mm. the Die Casting Process requires high budget and can pile up high initial cost. Die Casting method makes the metal porous up to some extent. In the Die Casting method the thickest section needs to be less than 13mm or 0.5 inches.