Die Casting Process, Cold Chamber Process, Hot Chamber Process

By: Kent Klein

Die casting is the method used for forcing molten metal intomold cavities under high pressure. Die casting is very versatile and hence, isthe widest used method for casting a metal. Die casting is same as permanentmold casting the only difference is that the metal is injected into the mouldat 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 diecasting are zinc, aluminum, copper, magnesium, tin and lead. Ferrous metals canalso be used for die casting, die casting method is generally used forapplications in which a large quantity is medium or small sized parts arerequired with detail, good dimension and fine surface finish.

There are namely two equipments used for die casting coldchamber and hot chamber process.

Cold Chamberprocess: In the cold chamber category of die casting, a cold chamber ofeach module is filled with molten metal. The time exposure provided for themolten metal to plunge the walls of the mold is less. This clod chamber processmethod is very useful for metals like aluminum, copper and metals that easilyalloy with iron at high temperatures.

Hot Chamberprocess: In the hot chamber process method of die casting, the pressurethat 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 isuncovered.

The die casting molds which are used in this method areexpensive and take usually take long production time. These die casting modulesare also called as “dies’

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Advantages of DieCasting: The method of die casting gives excellent dimensionalaccuracy. The dimensional accuracy is as good as 0.1mm for the first 2.5cms and0.005 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 astiny as 0.75mm approximately can be casted. Inserts like thread insertArticle Search, highstrength bearing surfaces and heating elements can also be inserted using theDie Casting method.Die casting alsohelps in reducing or even completely eliminating the use of secondary machiningoperations. The use of Die Casting method also helps to reduce the productiontime and a huge number of articles can be produced in a very short time. Diecasting method also helps to retain as well as increase the tensile strength ofthe metal. It offers tensile strength as high as 415 MPa that is 60ksi.

Disadvantages ofDie Casting: The casting weight is very less hardly between 30 gramsand 10 kgs. Also the size of the material that needs to be casted using the DieCasting method needs to small say around 600mm. the process of Die Castingrequires high budget and can pile up high initial cost. Die Casting methodmakes the metal porous up to some extent. In the Die Casting method thethickest section needs to be less than 13mm or 0.5 inches.

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