The difference between green sand casting process and resin sand casting process

Published: 17th March 2011
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In the past, one client asked us the difference between green sand casting process and resin sand casting process. Herein, I make a brief introduction to these two casting processes, and hope it could be helpful for other casting purchasers.

Green sand casting process is screening and mixing the wet sands, and filling the sands into the sand boxes, then use machines or just by workers to tamp the sands, then pouring the liquid iron into the sand molds.

Resin sand casting process is mixing the furan resin and sand together, then filling the mixed sands into the sand boxes, then after tamping, using the paints to flush the surfaces of molds, then burning the paints to make the sand molds to become very hard, finally, pouring the liquid iron into the solid sand molds.

1. Materials

The green sand casting process mainly uses the green sands as the molding material. The green sand is a kind of wet sand.

The resin sand casting process mainly uses the resin sand as the molding material, and need to use the alcohol paints.

Since the furan resin is more expensive, the resin sand castings will be more expensive than green sand castings.

2. Equipments

As for the traditional green sand casting process, it only needs sand boxes and workers, so no equipment needed. Today, more and more iron foundries in China use molding machines or automatic molding machines.

The resin sand casting process usually needs equipments to mix the resin sand and fill the sands into the sand boxes.

3. Production time

The resin sand casting process has an extra time to flush the paints, and burn the paints and wait the resin molds become hard. Therefore, it needs more production time, therefore, more costs.

If the green sand casting process uses the automatic molding machines, it will have very high production rate, one FBO molding line could normally produce 20 tons each day. Therefore, automatic molding line usually produces iron castings for the automotive industrial.

4. Casting quality

The casting quality has big difference for these two processes. Since resin sand casting process uses the hard molds, therefore, resin sand castings have better surface smoothness, higher dimensional tolerance, and less surface and inside casting defects, such as sand holes, air holes and shrinkage.

4. Suitable casting products

Resin sand casting process is suitable to produce large iron castings with weight range from dozens of kilograms to several tons.

Green sand casting process is suitable to produce small and medium castings with weight under 50 kilograms. Interestingly, as for the very large iron castings with weight of several tons, such as the dryer cylinders for the paper manufacturing machinery, the green sand casting process is the suitable choice. However, you can not produce so large castings by sand boxes, but just produce them by digging the large holes under ground.

Although there are so many differences between these two casting processes, it is not absolutely to judge your parts have to use certain casting process, the iron foundries should consider the suitable production process according to their technical conditions and capability.

The following photos are the green sand and resin sand casting workshops in Dandong Foundry in China.


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