The advantages and problems of sand casting process

Let me briefly introduce the advantages and problems of sand casting process, and hope it could be helpful for casting customers to learn more about its characters.

Advantages:

In China, 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 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 sand casting are lower. Therefore, the sand castings are cheaper than resin sand castings and shell molding castings. 

3. Higher production rate

The sand casting process can achieve high production rate. The floor molding with 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 sand can produce castings of 20 tons each day.

Moreover,sand casting process can produce the castings with unit weights from hundreds of grams to several tons.

The problems:

The disadvantages of sand casting process are also inevitable.

1. More casting defects

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 sand casting process are very rough and coarse. If the iron foundries use the very fine sand, the rough surfaces will be better. However, there are few iron foundries who use very fine sands in China.

3. Bad casting dimensions

Since the sand will have larger shrinkage, the casting dimensions will have larger changes during molding and cooing periods. Therefore, the 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 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.