Introduction to new die casting technology semi solid die casting

Semi solid die casting by most of Europe and the United States that is close to forming technology and new material preparation technology is one of the most promising new world, the liquid metal is good formability and solid metal forming quality together, so as to expand the application of die casting. For the production of heavy wall complex castings, non shrinkage holes, non porous casting castings, high strength and high performance castings, aluminum alloy is used instead of iron castings. The wall thickness can be obtained from 30~50mm aluminum and magnesium alloy parts. In developed countries, such as Europe and America, this technology has been used in large-scale production. As far as the United States is concerned, large semi solid foundry technology plants can produce tens of millions of automotive parts per year. Each casting weighs less than 10g and can be reduced to 10kg by a maximum of half a centimeter.

The principle of semi-solid die casting is applied to violent agitation in the alloy liquid cooling process, usually by mechanical stirring and electromagnetic stirring, only alloy dendrite fragmentation, a certain amount of slurry suspended spherical solid is obtained for die casting. There are two kinds of forming process

①Rheocasting
The rheo-casting will first heat the alloy ingot to the liquid metal, then stir the metal with the stirring technique to obtain the semi-solid slurry and finally to do the die casting.

②Thixotropic die casting
Die casting after semi-solid slurry is obtained, not products but with die casting, quenching ingots, etc. after cooling the ingot ingot cutting into the blank, and then the blank is re heated to semi-solid, then semi-solid metal forming die casting die casting machine with embryo.

The semi solid die casting is widely used, except that it enlarges the chance of using die-casting parts. Because of the high precision of the casting size, the casting surface is good and the surface is easy to be treated. The porosity, shrinkage, shrinkage and other defects are reduced, and the microstructure is fine. It can be heat treated and weldable. It also protects the die casting mould and prolongs the life of the die.
In the developed countries of Europe and America, the semi-solid die-casting technology of aluminum and magnesium alloy has entered the mature stage. Automotive parts, such as wheel hubs, brake cylinders, steering knuckle, support levers, cantilevers, valves, etc., are of high strength, high density and high reliability requirements. Semi solid casting can be used to achieve mass production of castings at low cost.