The anodizing polished aluminum profile is widely used in kinds of high-end civilian products, such as interior bathroom doors for home and hotel, and furniture products. The products made with polished surfaces are luxurious in appearance and can be colored or dyed according to requirements. The polished aluminum profile has great difficulty in production due to its serious surface quality. Especially in the long-term 6M mass production process, how to achieve quality stability and reduce waste is even more difficult in production. The strict management of each production process can produce a mirror-polished aluminum with stable quality. Below you can know the production process of anodizing polished aluminum profile.
Choose High-quality Aluminum Ingot.
The purity of the extruded aluminum ingot, the chemical composition, has a significant influence on the surface quality and polishing gloss of the extruded aluminum profile, so the high-quality aluminum ingot is the prerequisite for polishing the aluminum. The higher the purity of the ingot, the better the polishing effect of the extruded aluminum profile. The purity of the aluminum ingot depends on the content of metal impurities and non-metallic impurities in the aluminum ingot. The metal impurities mainly refer to Fe, Mn, Cu, Zn, Cr, Ti, etc. The most important of these impurities is Fe. The content of Fe is preferably controlled to be 0.1% or less. On the other hand, non-metallic impurities also have an essential influence. In addition to the selection of high-quality high-purity aluminum ingot, try not to add crushing scraps, especially anodized aluminum scraps.
Quality Extrusion Before Polishing
High-quality aluminum extrusion tooling die can improve the quality of subsequent aluminum surface polishing.
Production has to choose a suitable extrusion ratio. Too large or too small will affect the quality of the polished aluminum. For different types and extrusion ratio aluminum profiles, it is the key to ensure the uniform quality of aluminum polishing by achieving the same control extrusion temperature. Besides, the protection of the surface of the mill finishes extruded aluminum profile is also an essential part of ensuring the quality of the polishing.
Mechanical Polishing
Mechanical polishing is a significant part of an excellent mirror finish, especially for the 6M length aluminum profile. With a large polishing machine, this process serves the purpose of grinding and removing mechanical grain and also enables the surface to be polished.
Chemical Polishing & Anodizing For Aluminum Profiles
Mechanical polishing can give a good mirror effect, but aluminum is extremely oxidizable, so chemical polishing and anodizing processes are also required and necessary.
A typical chemical polishing method is tri-acid polishing. Tri-acid polishing is an essential process in the production of polished aluminum profiles. The polishing process must be strictly controlled to obtain a surface of high-brightness and low-defects.
HPO4 is the main content of the chemical polishing. The viscosity effect forms the mirror effect of the aluminum surface. The higher the content, the more obvious the mirror effect, so the HPO4 content is the critical factor in maintaining the polishing brightness. HNO3 is the main component directly involved in the reaction, and its content must be strictly controlled. The concentration is too high, not only will it produce a lot of yellow smoke, but also the reaction is too intense, difficult to control, and easy to create over-abrasive, sanding and dry marks and other defects. If the concentration is too low, the optimum brightness will not be achieved. The specific gravity and temperature setting of the bath are also an essential factor in ensuring the quality of the polished aluminum. The higher the specific gravity, the higher the temperature, and the better the brightness of the polished aluminum. However, if the specific gravity is too high, the temperature will be too high, and it will cause defects on the surface of the aluminum.
The anodizing process is the most severe process of matting in the production of chemical polishing products. The product is to ensure the surface brightness by using a low film thickness (≤5um), and the strict control of the anodizing process can minimize the extinction degree of the oxide film.
There are still many limitations to be solved in the production process of the anodizing polished aluminum profile. There are mainly the following aspects:
- The environmental protection treatment cost is too high, and the wastewater and waste gas generated in the triacid polishing are very serious to the environment. The NO2 produced in the tri-acid polishing and various types of acid mist pose a potential hazard to the operator’s body.
- Mirror polishing products have strict requirements on ingot casting, extrusion, mechanical polishing, chemical polishing, and anodizing processes due to their surface requirements, which make the price of mirror polishing products high.
- Product use is limited. Since the anodizing film thickness of the mirror polishing product is more senior than 6um, and the polished surface is matte severely in brightness, so the mirror polishing aluminum profile is generally only suitable for indoor products.
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