Aluminum alloy die-casting and aluminum alloy gold plating for cars are much more difficult than general copper plating, and the whole process of processing is also very complicated. The key reason is that the characteristics of die castings and aluminum alloys themselves are different from other metal materials. Aluminum is an amphoteric metal and reacts with acids and alkalis. If the solution is not good, it will lead to over-etching of the surface. And die castings and aluminum alloys are very easy to cause air oxide film whether in air or aqueous solution. If this air oxide film is not removed neatly, it will harm the bonding of the coating.

What is the reason for the oxidation spots of aluminum alloy die castings?

Common disadvantages of aluminum alloy die castings: Air oxidation welds are mostly distributed on the upper surface of the castings, at the corners where the metal mold is not ventilated. The fracture surface is mostly gray-white or light yellow, which can be found by X-ray fluoroscopy or machining and can also be found in alkali washing, pickling passivation or anodizing treatment. The test results show that adding a moderate preservative to the NaOH aqueous solution can produce a good actual effect of grinding and polishing.

The exploratory test also found that: After chemical polishing with a direct current constant current source with fructose NaOH aqueous solution under some standards, the transmittance of the aluminum profile surface can reach 90%, but because there are still unstable elements in the test, further scientific research is needed. . The feasibility analysis of using DC single-pulse chemical polishing method to grind and polish aluminum profiles under partial alkali standard was explored. slower

During the production and processing of die-casting parts, part of the aluminum-clad layer is drilled off, the surface layer is aluminum, and the inner layer is miscellaneous aluminum. The two materials are very different, so black spots like "white spot" appear after air oxidation.

Solution: It is usually not easy for customers to understand this situation. Manufacturers should do more presentation work and explain the causes and consequences to prevent misunderstandings. On the other hand, according to the forecast and analysis of the aluminum industry company, the use of automobile die-casting parts will increase by 50% within five years, from 250 pounds per vehicle in 2001 to 380 pounds per vehicle in 2006. Many production and manufacturing die castings must use polycrystalline diamond (PCD) CNC inserts. The main reason for the damage of cutting PCD CNC inserts during production and processing. To maintain the detailed drilling edge of the PCD CNC insert, the pipe drilling load is evenly distributed to each side edge of the turning tool.

Car die-casting annealing treatment: The aluminum alloy casting is heated to a higher temperature, generally around 300 °C, and after a certain period of thermal insulation, the process of cooling to the indoor temperature with the furnace is called quenching. During the whole process of quenching, the solid solution is dissolved, and the phase particles are aggregated, which can remove the thermal stress of the casting, stabilize the size of the casting, reduce the deformation, and expand the plastic deformation of the casting.

Conclusion

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