Lost wax castingThe craft is developed from the ancient casting craft. As early as the late Neolithic period more than 5,000 years ago, ancient craftsmen in my country had widely used the dewaxing casting process in the production of bronzes. According to the characteristics of plasticity and thermal volatility of beeswax, the craftsmen first carve the beeswax into the required shape, and then put the clay on the beeswax model, leaving a small hole, and roasting after drying to make it vaporize and volatilize. At the same time, the clay becomes a ceramic shell, leaving a female mold on the inner wall of the shell. At this time, the molten metal is injected into the shell along the small hole, and it is cooled and broken to obtain the required metal casting billet. The basic principle of contemporary lost wax casting process is no different, just more precise. It is mainly reflected in the higher requirements for the accuracy of the wax mold. In modern technology, the production of wax mold is not only the direct engraving of wax, but also the female mold can be obtained by silicone molding of the metal original mold (plate surface), and then the wax mold can be obtained after the silicone female mold is waxed. The casting material is no longer clay, but instead is replaced by gypsum. This product is much more sophisticated than the ancient casting.

Dewaxing casting process allowance: In order to ensure continuous solidification, it is sometimes necessary to increase the local allowance of the casting, and the additional part that exceeds the mechanical machining allowance is called the process allowance.

Dimensional tolerance of castings for dewaxing: see GB/T6414-1999.

Dewaxing type: Casting fillet radius R (mm) can generally be calculated according to the following formula: In the formula, "为" is the adjacent wall thickness of the cast iron, in order to avoid surface whitening, the casting fillet radius R (mm) can be calculated by the following formula calculate:

Dewaxing casting inclination angle: the size of the inclination angle of the casting is related to the relative position of the surface of the casting and the metal profile. When the casting is cooled, any surface that has a tendency to separate from the metal surface should be given a smaller casting slope; if the casting tends to be metal or core when it cools, a larger casting slope should be given; for example : For the holes and recesses on the castings, the casting inclination should be relatively large, generally 2°-7°, for the non-machined surface, it is 2°-3°, and the machined surface is 3°-7° .