Process of Dewaxing Casting Glass


  • Apr 19, 2019


Making Product Mould

Generally, the die is made of aluminium and steel, but it is inconvenient to use. The drawings engineering part of the factory is designed according to the drawings, and the gate is designed. Then, a series of processing with aluminium material through numerical control machine tools are used to manufacture the die.

Wax injection

After the die is opened, the wax injection operation can be carried out. Wax injection operation should pay attention to such factors as wax temperature, pressure and pressure of rubber mould.

The wax used in making wax models is usually blue model paraffin. Its melting temperature is about 60 C and the injection temperature is about 65 C. There are also other colors of paraffin wax, which have slightly different properties. The wax temperature and injection pressure are determined by the wax injection machine. There are usually two types of wax injectors: air pressure type and vacuum type. The wax injection principle of the two wax injection machines is basically similar, that is, the melted wax is injected into the rubber mold by air pressure. The difference between the two is that the vacuum wax injector can vacuum the rubber mould first and inject wax into the rubber mould, while the air-pressure wax injector can only inject wax directly into the rubber mould. So it is easy to operate vacuum wax injector, while air pressure wax injector needs some experience.

Finishing wax mold

Generally speaking, the wax mold after wax injection will have some problems more or less, such as flying edge, multiple edges, broken claws, naked eye trachoma, partial or overall structural deformation, small hole obstruction, unclear line of flower head, lace and so on. Surgical blades can be used to repair defects such as flying edge, multiple edges, unclear flower heads and flower head lapping; welding wax appliances can be used to repair sand holes and broken claws; welding needles can be used to penetrate small holes; and the deformation of wax patterns can be corrected in hot water at 40-50 degrees C.

In addition, for rings with different sizes, if you wait until you are in the mold to change the finger ring, it will undoubtedly be labor-intensive and material-intensive. Therefore, the general production enterprises are directly changing finger rings when repairing wax molds. It's very convenient to use the wax welder to change the finger ring. After welding, just trim the weld with a knife blade.

Welding tree group

After the wax pattern has been trimmed, wax trees need to be planted before further operation can be carried out.

Planting wax trees is to weld wax models in a certain order along the circumferential direction in order to get a wax tree which resembles a big tree, and then pour the wax trees into gypsum. The basic requirement of wax tree planting is that the wax models should be arranged in an orderly manner. The key is that the wax models can not be contacted. They can not only keep a certain gap, but also weld the wax models on the wax tree as much as possible. That is to say, the wax models on a wax tree should be planted as much as possible to meet the needs of mass production.

Shell making

Baking of wax mould is an important process to ensure normal casting. Generally speaking, the baking time of 18K gold mould is 6 - 12 hours, and that of platinum mould is 12 - 20 hours. The main functions of baking are dewaxing, drying and casting heat preservation. Taking the baking of 18K gold as an example, the dewaxing temperature is 0 ~ 350 C, holding time is 2 hours; the drying temperature is 350 ~ 700 C, holding time is 2 ~ 3 hours; the casting holding temperature is 600 ~ 500 C, holding time is 1 ~ 2 hours.

Finally, the molten steel is poured into the well-made shell.