The Surface Quality of Iron and Steel Castings

Surface smoothness and defectives are important quality aspects of iron and steel castings. Some steel casting purchasers may wonder why the surface quality of steel castings is worse than iron castings, such as lower surface smoothness, more surface sand holes, air holes, and sand residuals. Herein, we hope to explain this issue.

We can try to make a comparison list for the surface quality of all normal iron and steel casting processes from best to worst.

1. Best surface – steel castings produced by lost wax investment casting process. The lost wax silica sol or water glass materials will make the surface quality and smoothness of steel castings very good. No sand casting defects.

Steel Casting made by Lost Wax Investment Casting Process

2. Very good surface – iron castings produced by hot shell molding process. Hot shell and core molding process will use the yellow pre-coated resin sand as the molding material, which has very smooth surface and no sand residuals.

Iron Casting made by Shell Molding Process

3. Good surface – iron castings produced by molding machines or automatic molding line. Molding machine and automatic molding lines could cause the high and even molding pressure, which is very helpful to the surface smoothness and improve the defects.

Iron Casting made by Automatic Molding Line

4. Good surface – iron castings produced by very fine green sand. This kind of sand is very small and uniform, which is very good to the surface smoothness, but not every iron foundry use this sand since it is only suitable for producing small iron castings.

Iron Casting made by Fine Green Sand

5. Normal surface – iron castings produced by resin sand casting process. Furan resin sand is hard sand, so it has better surface quality, however, this process normally used for making large iron castings, so sometimes, the surface defects are inevitable. If your products are large, then resin sand will be the best choice.

Large Iron Casting made by Resin Sand

6. Normal surface – steel castings produced by lost foam casting process. This process is good for surface quality, as for the large steel castings, this process is the best choice, however, not many steel foundries in China can handle this process very well.

7. Normal surface – iron castings produced by normal green sand of hand molding. I do not need to say too much about this process, which is very common.

Iron Casting made by Normal Green Sand

8. Bad surface – steel castings produced by sand casting process of hand molding. Since steel castings need better air permeability to molding materials, so the size of sand used for steel castings will be larger than for iron castings, which is the main reason for worse surface quality.

Steel Casting made by Sand Casting Process

Herein, we just talk the difference of each casting process, but on the other hand, the quality of foundry sand, the pouring process and operation of workers will also affect the surface quality of castings.

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