Let me briefly introduce the advantages and disadvantages of green sand casting process in China, and hope it could be helpful for casting buyers to learn more about its characters.
In China, green sand casting process is very common, and almost all iron foundries could produce iron castings by this process. It¡¯s mainly because of the advantages of this process.
1. Simple production process
The production process of green sand casting is very simple comparatively, so easily handled. The materials are simple, and easily available.
2. Lower production costs
Since the materials are simple and its prices are lower comparatively, the production costs of green sand casting are lower. Therefore, the green sand castings are cheaper than resin sand castings and shell molding castings. As for the current cast iron prices, you could check the website of Dandong Foundry.
3. Higher production rate
The green sand casting process can achieve high production rate. The floor molding with green sand can produce castings of 100 to 200 sand boxes each day, e.g. about 100 pieces to 2000 pieces each day. The automatic molding process with green sand can produce castings of 20 tons each day.
Moreover, green sand casting process can produce the castings with unit weights from hundreds of grams to several tons.
The disadvantages of green sand casting process are also inevitable.
1. More casting defects
Green sand mold is a kind of soft mold, so it is not hard enough as the resin sand molds and shell molding. So, there are more casting defects such as sand residuals, sand holes, air holes and shrinkages.
2. Rough surface quality
The casting surfaces by green sand casting process are very rough and coarse. If the iron foundries use the very fine green sand, the rough surfaces will be better. However, there are few iron foundries who use very fine green sands in China.
3. Bad casting dimensions
Since the green sand will have larger shrinkage, the casting dimensions will have larger changes during molding and cooing periods. Therefore, the green sand casting process will cause larger dimensional tolerances. Normally, its could reach casting dimensional tolerances of CT10 to CT12.
4. Unstable casting quality
The temperature has some influence to the casting quality made by green sand casting process. Therefore, the iron foundries should keep the good temperature in cold winter. Moreover, as the manual floor molding, the worker's skill will have key affects to the casting quality.