The reason for the high dust content in steel shot is that the sulfur and phosphorus content exceeds the standard, and the breakage rate of steel shot increases

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　　Reasons and solutions for blackening of castings after shot blasting

　　Below, the editor will answer the reasons and solutions for blackening of castings after shot blasting

　　In the production process of castings, there will be a shot blasting process to improve the quality of the workpiece and clean the surface of the workpiece. Different types of shot blasting machines can be selected for different workpieces to achieve aesthetic treatment effects. However, we may also encounter castings with blackening on the overall surface or obvious black marks and spots in some areas after shot blasting. Some can be thrown away, while others have already been immersed in the casting substrate, and the area and position are not fixed.

　　The following is an analysis of the reasons for the above problems:

　　One Defects that existed before shot peening during the die-casting process:

　　1. Excessive use of black oil in die casting results in splashing of punch oil during mold opening and coating during die casting.

　　2. The product has been stored for a long time or at a humid temperature, with surface corrosion, severe mold or dust.

　　3. The dust removal device of the shot blasting machine has failed, and there is a lot of dust in the steel shot.

　　4. The operator did not wear gloves as required and directly touched the surface of the shot blasted casting with their hands, causing handprint marks.

　　5. After shot blasting, if left for a long time, the surface may accumulate dust or splash with water or oil, and the environment may become humid and oxidized.

　　6. The quality of the steel shot is unqualified, and the steel shot breakage rate is high, resulting in secondary pollution of the workpiece by dust.

　　II When the above situations occur, we provide the following solutions for everyone:

　　1. Defects do not cover the entire surface of the casting, but are controlled and managed by the die-casting process.

　　It is black oil, black in color, punch oil, dark red in color, coating, and a light color on the surface of castings with different colors.

　　2. After shot blasting treatment, the surface traces are shallow and cannot be removed because they have already been immersed in the casting substrate. Strengthen the management of product placement and avoid prolonged storage. If it needs to be stored for a long time, it must be covered and protected, and placed in a suitable environment.

　　3. The surface color of the entire casting turns black or dark, and dust removal should be restored or steel shot should be replaced.

　　4. Operators must be required to follow the operating instructions and wear gloves.

　　5. Shot blasting treatment should be promptly inspected for packaging, packing, and storage. If storage is required for a period of time, strict protection measures must be taken.

　　6. Replace qualified steel balls or high-quality precision machined steel balls to avoid secondary pollution of the workpiece.

　　The above is the reason and solution for the blackening of castings after shot blasting that our editor has answered for you.

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