What are the causes of rough and unsmooth casting surface? How to solve it?

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Time of issue:2020-06-06
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(Summary description)The rough and unsmooth surface of castings is a common casting defect, which is caused by the rough surface of the mold cavity and the chemical reaction between the molten metal and the surface of the mold cavity.

What are the causes of rough and unsmooth casting surface? How to solve it?

Categories:News
Author:
Origin:
Time of issue:2020-06-06
Views:23

Information

The rough and unsmooth surface of castings is a common casting defect, which is caused by the rough surface of the mold cavity and the chemical reaction between the molten metal and the surface of the mold cavity. It mainly reflects the following situations:

1. The particles of the embedding material are coarse and not fine after mixing.

2. The investment material is directly put into the muffle furnace after being solidified, but the moisture is too much.

3. When the temperature rises too fast, the expansion difference occurs at different positions in the cavity, which makes the inner surface of the cavity flake off.

4. The temperature of roasting is too high or the roasting time is too long, which makes the inner surface of the cavity too dry.

5. The melting temperature of the metal or the roasting temperature of the casting ring is too high, which makes the metal react with the mould cavity and the investment is burned on the surface of the casting.

6. If the roasting of the mould is not sufficient, molten metal will decompose the investment and more gas will be produced, which will produce pits on the surface of the casting.

7. After the molten metal is cast in, the local temperature in the mold cavity is too high, and the local roughness of the casting surface is produced.

The solution: A. Do not excessively melt the metal. B. The roasting temperature of the casting shall not be too high. C. The roasting temperature of the casting mold shall not be too low (the roasting temperature of the phosphate investment material shall be 800-900) d. The phenomenon of depression of the organization facing the casting track shall be avoided. E. Apply burn-proof liquid to the wax type.

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