An impeller is a rotor used to increase the pressure and flow of a fluid. It is the opposite of a turbine, which extract energy from, and reduces the pressure, of a flowing fluid. The impellers can be divided into below 3 types:
Enclosed impeller: consists of a blade and a front and rear cover plate. The efficiency of closed impeller is higher and the manufacturing difficulty is greater. It is most commonly used in centrifugal pumps. It is suitable for transporting clean liquid with small viscosity and no particles
Semi-open impeller: generally, there are two kinds of structures: one is the front semi-open impeller, which is composed of the back cover plate and the blade. The impeller efficiency of this structure is relatively low. In order to improve the efficiency, an adjustable clearance seal ring is needed. The efficiency is basically the same as that of the closed impeller, and the blade has the sealing function of the back blade or the auxiliary impeller in addition to conveying liquid. The semi – open impeller is suitable for conveying liquid containing suspended solids, fibers, etc. In recent years, the application of semi-open impeller in centrifugal pump for oil refining and chemical industry is gradually increasing, and it is used to transport clean water and similar liquid.
Open impeller: impeller with only blade and blade reinforcement, no front and rear cover plate. The number of open impeller blades is less 2-5. The impeller of water pump has low efficiency and less application. It is mainly used for conveying liquid with high viscosity and slurry.
Cast stainless steel impeller is widely used not only in pumps, but also in some industrial equipments. Because of stainless steel casting, the strength of impeller strength is always higher than other materials.
Why Stainless Steel Casting for Impeller?
The service life of stainless steel impeller is guaranteed, not easy to damage. Even after the use for a period of time, it can still be kept stable, prevent the occurrence of rust. In addtion, stainless steel casting can customize impellers in different specifications and sizes according to different uses. So, it is undoubtedly a good choice to produce impeller by stainless steel casting.
Stainless steel casting can creat impellers with high strength and stable performance. However, the quality may be different. Like CFS Foundry, the quality of cast stainless steel impeller is always best. So, it is important to select a reliable stainless steel casting manufacturer.
Stainless steel impellers are widely used in a variety of environments, running efficiency is also very high. The use of stainless steel material help to ensure its serving life, but also put an end to the short time of damage.
Stainless Steel Impeller Casting Process in CFS Foundry
- Patterns Making: The so-called pattern making is to first make a wax mold with the appearance and shape exactly the same as the stainless steel impeller we need, but with a slightly larger size. Here, considering the shrinkage of the stainless steel and the pattern material, the size of the wax pattern is slightly larger than the size of cast impeller. The wax pattern is formed by pressing molten wax material into the tooling for solidification.
- Shell Forming: It is the process that coating the wax pattern with a layer of fire-resistant paint, and then to be sprinkled with sand, so after a period of hardening, the surface will form a layer of fire-resistant thin shell.
- Dewaxing: In this process, the shell will be put into the heating oven. Under high temperature, the wax material in the shell will be melted fully. Then, dry the shell to prepare for casting.
- Pouring: Pouring liquid stainless steel into the shell, and waiting for solidification under room temperature.
- Post Treatment: After cooling, knock the shell and cut the sprue gate by grinding machine to achieve net shape impeller castings. Then, shot blasting to move mill scales and smooth the surface.