The characteristic of die casting
High Pressure die casting or gravity casting, is a molten gold poured into the pressure chamber, to the high speed filling steel mold cavity, and the alloy liquid under pressure solidification and casting method. Die casting is distinguished from other casting method is mainly characterized by the high pressure and high speed. The metal liquid is under pressure to fill the cavity, and at higher pressure solidification under common pressure, 15 to 100MPa. The liquid metal to the high speed filling cavity, usually in the 10 – 50 meters / second, some still can exceed 80 m / s, ( through the gate into the cavity of the line speed gate speed ), thus the filling time is very short, about 0.01 – 0.2 seconds ( must be considered casting size different ) can fill the cavity. Die casting machine, die casting alloy and die casting is a casting production of the three elements, are indispensable.
die casting process is called the three major elements of organic ground be used, enabling stable rhythmically and efficient production of appearance, inherent quality good, size consistent with patterns or the agreement in accordance with the requirements of qualified casting, even high-quality casting. Die casting is a kind of precision casting method, through casting and metal die-casting dimension tolerance is very small, the surface accuracy is very high, in most cases, die castings without further machining to assembly application, threaded parts can also be directly cast.
From the general photography, typing machine, mechanical computing devices and accessories and other small parts, as well as the automobile, locomotive, aircraft and other means of transport complex parts using mostly die casting manufacturing.
Die casting method also has the following shortcomings:
( 1) Die Casting Alloy is restricted at present only zinc, tin, lead, copper, magnesium, aluminum and other six kinds of copper alloy, with the highest melting point. Recently there have been reports of cast iron casting, but for the sake of economic factor, must be related to the research of materials, mold materials and operation method.
( 2 ) expensive facilities needed equipment such as the production of the die casting machine, melting furnace, holding furnace and casting mold costs are quite expensive.
( 3) the casting of poor airtightness due to melting liquid by high-speed filling to die when, can produce turbulence phenomenon, the local formation of a stoma or shrinkage, influence the airtightness of castings. There is currently an IMPREGNATION processing method, can be used to improve the resistance to airtightness.