To make a high-quality casting, it is not enough just to melt the metal, pour it into a mold prepared in advance, and let it cool. This will result in a product of low strength, with uneven surfaces. To avoid this, injection molding is used. The technology is based on the use of industrial equipment that creates a working environment for the production of quality castings.
The best type of injection molding
Cold chamber die casting
is an efficient way to manufacture complex metal parts. A special chamber is filled with molten metal, which is designed to compress the material. When the pressure rises, the molten mixture fills the metal mold at high speed. The compression chamber can maintain the melting temperature of the material up to 450 degrees. There are three types of technological processes, depending on the filling rate of the metal structure:
1. Low speed - up to 2.5 m/s. The technology is used to manufacture parts with thick walls.
2. Average speed - up to 15 m/s. The metal fills the mold with turbulent movements. The center of the casting is filled with air bubbles, which are removed under the influence of heavy loads.
3. High speed - more than 30 m/s. The molten material is fed at such a speed that it is sprayed over the surface of the machine. This entrains a large amount of air, which degrades the strength of the casting. To remove the air, high loads are injected - about 500 MPa.
Fields of application
The technological process of casting under load makes it possible to obtain castings with a high strength index. Due to the effect of high pressure, air bubbles escape from the product, which has a positive effect on the mechanical properties of the material. Application of this technology:
● manufacture of carburetors for cars;
● creation of plumbing details;
● manufacturing of parts for household appliances.
● manufacturing of parts for computers and various electronics.
Cold chamber die casting produces a small pressure (up to 100 MPa). The master must pour the molten material into the chamber, which is intended for pressing. Further, under the influence of loads, the future product is sent to the mold where the metal crystallizes. After that, the movable elements open the structure for solidification. A rod is removed from the workpiece, after which a free cavity remains. The press pushes the product outward. Machines with cold chambers do not allow thin-walled parts to be produced due to the rapid cooling of the material.
Metal injection molding has several stages, which must follow strictly one after the other. If the technology is violated, the result will not be correct. Stages of work:
● A mold is made to create castings.
● It is attached to the machine.
● The metal is melted and fed into the pressing chamber.
● Under the influence of increasing loads, it is poured into the mold at high speed.
● Further, the material crystallizes, at the same time the working piston begins to act on it.
● When the product is ready, the holding structure automatically opens. Moving elements squeeze parts out of the machine.
● Automated equipment requires a master to control moving elements, check blanks. The manufacture of structures for creating castings of complex shapes requires accurate drawing, the use of high-strength alloys, and metals. They must withstand loads exceeding 500 MPa.