Permanent mold casting is a process of casting metal that employs reusable, or permanent, molds. It is named chill casting too. In our factory, we have two types permanent mold casting process
The permanent mold casting process is used in a variety of applications where a project will see mass production or duplication of the project is necessary. Although the process is more expensive than sand casting and high pressure die casting, it is considered to be a cost-effective means of part replication for most major industries.
The mold of permanent mold casting is made from steel or iron. So the mold cost is more expensive than sand casting molds, but the surface is better than sand casting. But the mold of permanent mold casting is more cheaper than high pressure die casting tooling.
In most cases, permanent mold casting is done by using a two-piece mold. These molds are usually made from steel or iron.. The two parts of the mold fit together snugly and have an opening at the top for the molten metal to enter. After cooling, the two pieces of the mold are separated, and the cast metal part is retrieved for finishing. If the structure of casting is very complex, there are some slits on the mold. Sometimes, Foundries have to do core tooling, install cores into mold. After casting, take out cores.
To start the process, the mold is preheated. This step removes any moisture that might be present in the mold and keeps the molten metal from cooling too quickly. The preheating of the permanent mold also prevents damage to the mold as a result of thermal expansion when the molten metal is introduced to it.
The process of permanent mold casting employs several means of introducing molten metal to the mold. The most common method is the use of gravity to simply pour the liquid metal into the heated mold. This method is the least expensive method of permanent mold casting because it requires less equipment, but it is not suitable for situations in which the liquid metal might not reach all areas of the mold.
In situations where the permanent mold has fine details that must be filled with molten metal, vacuum- or pressure-assisted introduction of the metal might be necessary. Which is called low pressure die casting Process.
Special Features of Permanent Mold Casting process:
❖ Produce smoother cast surface finish compared to other castings
❖ Better mechanical properties
❖ Can cast thinner walls
❖ Other inserts and pins can be casted on the part
❖ Produce parts that are lighter in weight
❖ Economical and cost-effective
❖ Lessen or eradicate secondary machining operations
❖ Good dimensional accuracy