The yellow area is the coating part.
The first step in the yellow area is to mix the coating, and choose the rheo cast steel coating. The mixing ratio of the coating and water is 1:0.75, the mixing time of the coating is 2.5 hours, the mixing time is half an hour after two hours of slow mixing, and the Baume degree after mixing is 1.7 to 1.8.
In the process of coating application, it is necessary to brush. When the brushed model is brushed again, it is not allowed to soak in the paint tank for too long, otherwise the paint will fall off. After each application, the next application shall be carried out after the paint has dried completely. The painted model is placed in the drying room for drying. The temperature and humidity of the drying room affect the quality of the model. The temperature is set between 45 and 50 degrees. In the drying process, the white model cannot be too close to the heating, otherwise it will cause the internal deformation of the model, but it is difficult to find the coating cover on the surface, and the casting will result in defective products. The humidity is controlled by the exhaust fan, and the paint will not dry completely due to excessive humidity. During the, the moisture contained in the wet model will vaporize when encountering molten iron, and the water vapor will cause the phenomenon of “shooting” upward. The thickness of the finished model coating shall be between 1.5-2.5mm. If the thickness is poor, the permeability is poor, and if the thickness is thin, the fire resistance is not enough.
Suggestion: because the white mold made by the molding machine is composed of two butt joints, there is a gap between the two halves of the white mold, and the inside of the white mold is a cavity, so the water vapor will enter the cavity through the gap during the drying process, so it is recommended to cut the riser top after the last coating, so that the inside of the model can also be ventilated and ventilated, to remove the moisture entering the inside of the model.
According to the weather temperature of the site, heat preservation measures shall be taken during the process of delivering the model from the white area to the black area. Because the temperature difference from the drying room to the outdoor is too large, the coating will be separated from the bone, and the white model will shrink when it is cold, and the coating will peel off.