Smokeless mirror polishing technology for aluminum alloy profiles

1. Technical Features and Advantages of Alloy Aluminum Plates and Other Aluminum Alloy Profiles

(1) Technical Features of Alloy Aluminum Plates and Other Aluminum Alloy Profiles: Smokeless mirror polishing has characteristics such as no yellow smoke, no streaks, low cost, low consumption, low equipment investment, high brightness, high stability, high efficiency, and high yield. It overcomes the bottlenecks and defects of traditional polishing techniques, successfully achieving large-scale production of 11-meter-long chemical-polished materials as well as automated line chemical polishing. Smokeless mirror polishing technology is an upgraded replacement of ordinary tri-acid and electrolytic polishing and represents the development direction of chemical polishing technology for alloy aluminum plates and other aluminum alloy profiles.

(2)The technical advantages of aluminum alloy sheets and other aluminum alloy profiles are as follows:

1) No yellow smoke: Smokeless mirror polishing fundamentally solves the problem of large amounts of yellow smoke generated by triple-acid polishing. It can save a significant amount of environmental treatment costs and clears the main obstacle for the widespread use of chemical polishing.

2) No streaks: Smokeless polishing technology completely solves the problem of polishing streaks and enables fully automatic production of 11-meter-long polished materials, making polishing as easy to operate as alkali etching.

3) High brightness: Due to the use of new polishing components, smokeless polishing increases brightness by 20%–30% compared to triple-acid polishing and electrolytic polishing, making it the brightest polishing technology currently available.

4) Low consumption: The consumption of smokeless mirror polishing agents can be reduced by 60%–70% compared to electrolytic polishing (500–700 kg/t of material).

5) High yield: The smokeless mirror polishing process produces almost no defects, resulting in a very high product yield.

6) High production efficiency: Smokeless polishing can accommodate a large amount of material at once, allowing multiple rows to be polished each time; there is no waste material in polishing, and production efficiency is at least twice that of triple-acid polishing and 6–9 times that of electrolytic polishing.

7) Stable bath solution: The smokeless mirror polishing bath hardly requires adjustment and can operate stably for a long time, paving the way for large-scale industrialized and automated production of chemically polished aluminum materials.8) Stable brightness: Polished materials from different production batches maintain stable brightness because the bath is not adjusted.

2. Analysis of Process Flow and Operation Key Points

(1) Explanation of Tank Positioning:

1) The smokeless mirror polishing tank is fronted by a completely enclosed exhaust wall, preventing external natural wind from reducing exhaust efficiency, which is beneficial for all-weather production during rainy or foggy days.

2) The width of the smokeless mirror polishing tank is over 1.6 meters, enhancing the tank liquid's buffer capacity to absorb smoke, which is conducive to large-scale batch production.

(2) Explanation of Tank Liquid Functions:

1) Wax and Scale Removal Tank: This tank contains a new type of mild alkaline wax and scale remover, capable of removing mechanical polishing wax and residual heavy grease without corroding aluminum alloy. It is easy to operate.

2) Smokeless Mirror Polishing Tank: This tank contains multiple components, enriched with strong oxidizers, which can perform mirror polishing on aluminum alloy. Compared with other polishing technologies, this tank has the following characteristics:

① Absolutely no yellow smoke, stable brightness: This bath contains a sufficient amount of smoke suppressant, completely inhibiting the formation of yellow smoke; since strong oxidants decompose slowly, the concentration is more stable than that of the triacid bath, resulting in much smaller brightness differences between different batches of aluminum alloys compared to triacid polishing.

② Increased brightness: The brightness of chemical polishing not only depends on the concentration of phosphoric acid and nitric acid, and temperature, but also on the water content of the polishing solution. The higher the water content, the lower the brightness; in triacid polishing solutions, the phosphoric acid content can reach up to 80% (with a water content of 15% for the phosphoric acid), resulting in a solution water content of less than 12%; such high water content inevitably reduces the brightness of the polished material. During the production of smokeless mirror polishing solutions, long-term high-temperature concentration ensures the water content is as low as 5%, thereby significantly enhancing the brightness of the finished material.

③ Can be dripped for a long time: Considering that the chemical polishing reaction is too vigorous, when aluminum alloys leave the bath, the dripping time cannot exceed 20 seconds, otherwise a large amount of polishing solution would be carried into the water wash bath, making the cost of the polished material too high. The smokeless mirror polishing solution contains a sufficient amount of corrosion inhibitor, which protects the aluminum alloy after leaving the bath, allowing it to drip in air for any length of time without causing blemishes or streaks. This can save more than 70% of the polishing solution.

④ Automatic ash removal: When aluminum alloys are impure or the polishing solution is aged, aluminums often have a layer of black ash after triacid polishing, which is difficult to remove by conventional methods and seriously affects the quality of the polished material. The smokeless mirror polishing bath contains ash-removing components that can automatically remove polishing ash.

⑤ High yield: Since the mirror polishing bath solves issues such as color differences, streaks, blemishes, and polishing ash, the yield is significantly increased, thereby reducing costs and improving production efficiency.

3) Bright-preserving oxidation tank. This tank is set up for two main purposes:

① Pre-forming chemical oxide film: The bright-preserving oxidation tank can generate an oxide film of a certain thickness while completely maintaining the original brightness. Before aluminum alloy is anodized from a mirror polish, it can first pass through the bright-preserving oxidation tank to pre-form a chemical oxide film of a certain thickness. This prevents pitting or streaks in the washing tank before oxidation, improves the yield, and also reduces brightness loss during anodizing.

② Fine removal of polishing residues: Polishing residues originate from two sources: inclusions in the aluminum alloy and aging of the polishing solution. Polishing residues are difficult to remove by general methods and can seriously affect the appearance quality of polished materials. Although the smoke-free mirror polishing tank contains a residue remover that can eliminate most polishing residues, a small amount may still remain. The bright-preserving oxidation tank can thoroughly remove polishing residues, thereby ensuring the quality of polished materials.