The Sand Casting Process in China
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|The Sand Casting Process in China|
|Sand Casting’s Pros and Cons|
An extremely well established industry in China, it also lays claim to being one of the first countries to have invented the sand casting process.
While the Chinese sand casting industry produces both non-ferrous and ferrous castings, aluminium sand casting occupies a significant and growing part of the industry. In fact, this occupation is so big that it serves both the domestic markets as well as the international markets.
In China, the processes used to cast aluminium are the same as those used elsewhere in the world. This fact allows for the work to be readily transferred from other manufacturers to foundries in China. This also allows Chinese foundries to take full advantage of the worldwide pool of equipment, processes and the latest material development, even though China itself has an extensive pool of suppliers as well.
The sand casting process has four stages that can be summarised as follows:
The pattern making stage
During this stage, patterns are made using a wide variety of materials and techniques. Simple patterns are made by skilled craftsmen suing wood, making allowance for shrinkage and other factors. The sprues, runners and gates are added to ensure that the casting cavities are all properly filled. If required, pattern makers will also produces cores, which allow for the creation of voids in the casting.
For more complex patterns, computer systems are used to create a more optimised mould design. This computer is also able to feed output data to the computer controlled manufacturing equipment. Tools like this are often produced in aluminium and used for higher production volumes.
Mould and Core Making
The process of making the mould can be either manual or automated and it is present in the casting process to ensure that the pattern (made in the first stage) is impressed into the sand and that the casting sand is suitably compacted to ensure the removal of the pattern piece, cores and the other fitting parts of the mould tool. While some casting processes make use of resin based systems to assist with the casting mould integrity, other processes make use of carbon dioxide assisted curing techniques.
The casting (or pouring stage)
Once the casting mould has been assembled, the metal that is to be casted, is melted in a furnace of a cupola (depending on the size). Great care is taken in order to control the melt. Frequently, the composition of an alloy will be examined and constituents adjusted to ensure that none of the properties of the alloy is lost. The metal is then poured into the sprue until the mould cavities are filled. This pouring can be either manual or automated, depending on the level of automation and scale of the foundry.
The break out
After cooling for a certain period of time, the sand mould is broken out and the product is revealed. This stage in the processes is often done with the help of automated vibrating equipment. Because Chinese manufacturers produce outputs that serve a wide range of export markets, they work to a wide range of international standards.
Well established in China, its aluminium stand casting processes are not only wholly compatible with global markets, but also work to internationally recognised standards.
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