There are two casting methods for investment casting in commonly used. The first one is gravity casting method with hot type. This method is the most widely used in investment casting now. The shell removed from the baking furnace and performed at a high temperature by pouring. However the metal always be cooled slowly in the shell and filling the casting under a high mobility. So casting could copy the shell shape better and while improve the precision of the casting. Certainly the slow cooling will make the coarse become grain. That will decrease the mechanical performance of casting. During the pouring time, the surface hardness, surface finish and size prevision of casting surface also have been decreased greatly.
Another casting method is vacuum suction casting. Put the shell in the pouring box with vacuum. Sucking the gas in the cavity through the micro pores in the shell. So liquid metal could filled the cavity better.
After coating with a layer of shell each time, we should drying and hardening it. That make the binder in coatings change into gel and connect with refractory material. After the shell harden completely, we need to fused the module. The module is usually made of wax pattern material, so we called this process as dewaxing.