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7 Types of Metal Casting

August 13, 2020

Casting is a process that is used in the metal industry to produce numerous objects and parts. Basically, liquid metal is poured into a specific mold and left to harden, after which it is removed from the mold and put through different finishing processes, or on the other hand, used as a finished item.

This process is most commonly used in the automobile industry. Did you know that one vehicle consists of 100 parts created this way? Besides, it is also used in the machine, construction, energy industry, and even for designing and manufacturing jewelry and art pieces.

The main reason why casting has been used for thousands of years now is that it allows us to get the exact shape and size of the object we need. Plus, since metal is always involved, by creating the right mold, we are able to get an item that not only meets all the requirements, but that is also sturdy and durable, which means that it is going to last for a long time.

Since this process is so complex, it is divided into two principal categories – expendable and non-expendable. Furthermore, according to the material that the mold is made from and the method used, there is another division. When it comes to the former one, it can be sand or metal, and the methods can include low pressure, gravity, and vacuum.

Sand mold casting

Due to the fact that this type of mold can be used to manufacture either a small or a large number of items, of the smallest size and unique shape, as well as the fact that it is cost-effective, this kind of metal casting is the most popular one. There are actually no boundaries when it comes to manufacturing items this way. A single one can be used, or a different number of molds can be designed to create the item, which is then assembled together.

Different kinds of sand grain can be used – smaller and bigger ones, as well as the ones that are of irregular shape, and as you can assume, each of these has certain benefits. When it comes to mold, these can be made from dry or wet sand, and in order to get it to be of right density, the sand is mixed with clay, water, and chemical binders. Naturally, the pump casting process is used during the manufacturing, and if you are interested to learn more about it, or explore the machinery, visit dawangcasting.com.

Shell molding

Even though it is quite similar to the previously described molding, this one provides manufacturers to create thinner molds, which means that they get to save a lot of material, and therefore, a lot of money. The thickness of the sand one is between 100 and 200 mm, while the thickness of this one is only between 3 and 10 mm. You have to admit that this is a significant difference. In order to get this shell, the sand is bonded with resin, and then the mixture is put on a surface that is heated up to 250° or 300°. Since the resin melts at 60° to 90°, it binds the sand around the mold, therefore, creating a hardened shell. This process only takes between 40 to 60 seconds, which is another reason why this method is widely used.

Evaporative mold casting

As you can assume from its name, the ones that are used in this casting process are made of compounds that start evaporating when the metal is poured into them. There are two main benefits to this method. Firstly, one-piece mold is used, meaning that you will immediately get a finished product since it won’t have to be assembled when the metal hardens. Secondly, there won’t be any edges on the item that require another finishing process. These imperfections cannot be avoided when some other method of casting is used, and this evaporative one is recommended for simple molds that do not have a core.

Plaster mold casting

This method of casting is very similar to the first one that we have talked about, but in this case, plaster is used instead of sand. The plaster is mixed with water and then poured over a model to create a mold. The benefit of this one is the very high precision, which allows manufacturers to create intricate designs of products. The only downside is that these have to be baked, and what’s more, they can only be used materials that have a low melting point, such as zinc, copper, magnesium, and aluminum.

Vacuum mold casting

The main tool for creating molds via this method is heated foil. Once it cools down, it is put into a model, then the sand is poured over it, and finally, it is covered with another piece of foil. Now begins the vacuum forming, so the mold is produced.

Permanent mold casting

The main feature of this type of casting is that reusable materials are used, which are usually graphite or steel. Materials that are cast this way are multiple – zinc, aluminum, magnesium, copper and lead alloys, and so on. The type of casting used is usually the gravity one, but this doesn’t mean that vacuum or gas pressure cannot also be utilized.

Centrifugal casting

The process that occurs here is quite obvious – when the metal is poured into molds, which are affected by the centrifugal force, so they constantly rotate. The trick with this method is that the power of the force must be exact in order to prevent the spillage of liquid metal and to ensure that the design of the product is perfect, meaning that there aren’t many marks or damages.

Since this process allows manufacturers to create items with great precision, as well as work on the tiniest details, this casting is very popular when it comes to jewelry pieces and small artworks.

To sum up

In this article, we have mentioned only seven types of casting, but as you can assume, there are many more. Since we have provided you with some essential information about these, if you want to learn more, check detailed guides online that will take you through every aspect of the process.

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