The methods of Silica Sol precision casting include sand casting, special casting, precision casting, V-method casting. The precision casting in investment casting belongs to special casting. When we are casting silica sol, we all know what is the casting process of silica sol?
The casting process of silica sol is as follows:
Step 1： Press the wax pattern
The treated wax paste is pressed into the mold cavity, and then taken out after being condensed by the ice water machine. After being put into the pool for a period of time, a single wax mold is obtained after being repaired and inspected. Wax pattern can be understood as a kind of pressure casting parts.
Step 2: Making tooling mold
A mold is a mold used to press the pattern of a casting. In order to ensure the quality of wax pattern, the mould must have high dimensional accuracy and small surface roughness value.
Step 3: Wax pattern repair
The quality, surface quality and deformation degree of wax pattern determine some important parameters of the product. Therefore, the wax mold workshop needs constant temperature control to minimize the wax mold deformation. At the same time, the surface inspection of each wax mold is also required. The flow marks should be removed. Meanwhile, the burr, flash and mold line of wax parts should be removed for mold repair, and minor defects should be repaired.
Step 4: Wax pattern combination (tree building)
After repairing the wax pattern, in order to improve the productivity of qualified single wax mold, the single wax mold is fused and welded on the wax common gating system prepared in advance to form wax pattern group. Generally, 2-80 wax models can be fused and welded on one wax model group.
Step 5: Clean the wax pattern
After standing for more than 45min, the wax pattern group can be cleaned. Before hanging slurry on the shell, the wax pattern group after the number of groups must be cleaned to remove the wax chips and grease on the surface and improve the adhesion of shell making.
Step 6: Shell making
After the wax pattern is dipped and hung, it is put into the shell making room for drying. The surface layer is dried naturally, and the transition layer and back layer are dried by rotary air drying method. The coating is repeated for 5-7 times (5-6 layers for small castings and 6-9 layers for large castings).
Step 7: Shell baking, pouring, sand dropping and cleaning
After dewaxing, the shell should be roasted during pouring. The shell should be roasted in an oil fired or electric furnace at 1100 ℃ for 50 minutes. The main purpose is to remove the residual wax after dewaxing, improve the strength and permeability of the shell, and prevent the shell from deformation or cracking during pouring.
Step 8: Dewaxing and wax treatment
The shell is poured into the steam dewaxing axe to melt the wax pattern and flow out from the bottom. After separation by water separator, the wax liquid is collected and put into the dewaxing bucket for further wax water separation and impurity removal.