After the quick-drying silica sol coating is prepared, the shell making operation steps such as sanding/floating sand are the same as those of ordinary silica sol. However, due to the addition of quick-drying agent, the process environment in the shell-making room can be properly adjusted, especially the wind speed control. When most enterprises use ordinary silica sol surface coating to make shells, in order to prevent the surface coating from drying too fast and cracking, they intentionally raise the humidity standard between the surface layers, and do not allow the surface coating to assist air flow. However, due to the addition of macromolecules of quick-drying agent, the quick-drying silica sol coating has better toughness in the process of dehydration and drying, so according to practice, the surface layer can also be properly assisted with air blowing to speed up water evaporation. As for the temperature of the shell-making room, the drying time between layers is shorter in the process of quick-drying silica sol shell-making, so the temperature of the shell-making room can be appropriately increased. The practice shows that the temperature range is about 5 ℃ higher than that of the ordinary silica sol process, which has no effect on the casting size. The temperature, humidity and wind speed parameters recommended by the standard are shown in the table.
Of course, the geographical and climatic environment of each enterprise is different, and the specific environmental temperature and humidity can be adjusted according to the product quality requirements, regional environment, seasonal changes, etc; In areas with high humidity and low temperature, the wind speed can be appropriately increased or increased.
| Hierarchy | Temperature/℃ | Relative humidity (%) | Wind speed/m · s ^ – 1 |
| Surface course | 25±3 | 50~75 | 1.6~3.3 |
| Transition layer | 25±3 | 45~65 | 3.4~5.4 |
| Reinforcement layer | 27±5 | ≤ 60 | 5.5~7.9 |
| Slurry sealing | 27±5 | ≤ 60 | 5.5~7.9 |
It should be pointed out that the wind speed in the standard is the wind speed relative to the module, which can be measured by installing an anemometer in the module accessories. At the same time, the comparison method of infrared temperature measurement recommended by Professor Chen Bing of Beijing University of Aeronautics and Astronautics is also cited in the evaluation of the drying effect of the mold shell.
The standard meets the requirements of national green development and environmental protection development, and specifically specifies that the materials and process pollutants involved in the shell-making process should comply with the provisions of GB/T 32251.