ShengHui factory casting process introduction:Make Mold & Wax Pressing & Tree Assembly

1.SILICA SOL CASTING PROCESS
The castings produced by silica sol casting process have high dimensional accuracy, which can reach CT4-8 level specified in GB16414-1986, low surface roughness value, which can reach Ra0.8-6.3um, small processing margin, and even can realize no cutting processing; Silica sol casting process can also produce more complex geometric shapes of castings, the minimum wall thickness of castings up to 2.5mm, the minimum aperture up to 1mm, casting weight :max.60Kg,min.0.003Kg .casting length :min.10mm; The main casting materials are carbon steel, alloy steel, stainless steel, copper alloy, aluminum alloy. But the casting cost is twice as high as the water glass precision casting process. There are three kinds of wax , modified wax and low temperature wax in silica sol casting process. The products made with medium-temperature wax have the highest precision and the best surface roughness, but also the highest cost; Modification followed, low temperature wax was the worst, but the cost was also the lowest.

2.SHELL MOLD CASTING PROCESS
Shell-mold casting process is also known as shell molding process. It is an expendable mold casting process that uses a resin covered sand to form the mold. In shell-mold casting process the mold is made like a shell. The thin or hollow mold is used so that weight of mold is less and handling of mold becomes easier.
To manufacture the thin mold, the phenolic resin with small addition of silica sand are used as mold material. For making shell-mold casting requires the use of a metal pattern, oven, sand-resin mixture, dump box and molten metal.
Shell-mold casting allows the use of both ferrous and non-ferrous metals, most commonly used molten metals are grey cast iron, ductile cast iron, carbon steel,aloy.steel,stainless steel, aluminum alloys and copper alloys.

3.Steps of Shell Mold Casting
1. Pattern creation – A two-piece metal pattern is created in the shape of the desired pattern required.
2. Mold creation – First, each pattern half is heated to 175-370°C and coated with a lubricant to facilitate easy separation from the pattern formed. Next, the heated pattern is clamped to a dump box. The dump box is inverted, allowing this sand-resin mixture to coat the pattern. The heated pattern partially cures the mixture, which now forms a shell around the pattern. Each pattern half and surrounding shell is cured to completion in an oven and then the shell is ejected from the pattern.
3. Mold assembly – The two shell halves are joined together and securely clamped to form the complete shell mold. If any cores are required, they are inserted prior to closing the mold. The shell mold is then placed into a flask and supported by a backing material.
4. Pouring – The mold is securely clamped together while the molten metal is poured from a ladle into the gating system and fills the mold cavity.
5. Cooling – After the mold has been filled, the molten metal is allowed to cool and solidify into the shape of the desired casting.
6. Casting removal – After the molten metal is cooled, the mold is broken and the casting is removed. Trimming and cleaning processes are performed to remove any excess metal from the feed system and to separate small sand particles from the mold.