CNC Machining: Surface Treatment Methods and Aluminum Alloy Characteristics of Aluminum CNC Machining Parts After Filming

Aluminum has the advantages of low density, high specific strength, good corrosion resistance, good electrical and thermal conductivity, good weldability, good plasticity, easy CNC machining and forming, and good surface decoration properties. Aluminum alloy is made of pure aluminum by adding some alloying elements. Aluminum alloy is better than pure aluminum, and aluminum has better physical and mechanical properties.

Due to the relative activity of aluminum, it can spontaneously form an amorphous oxide film in the air, making it have better corrosion resistance in the atmosphere, but the film thickness is only about 4nm, and the structure is loose, thin and thin. Porous, low hardness, poor wear resistance, and low mechanical strength, so it is necessary to manually cover the surface of aluminum CNC machined parts with a film to achieve the purpose of protection. It can usually be achieved by oxidation treatment, electroplating and external coating.

The oxidation treatment mainly includes anodic oxidation, chemical oxidation and micro-arc oxidation. Xu Lingyun used three different methods to study the mechanical properties and corrosion resistance of A 356 aluminum alloy. Surface treatment chemical oxidation, anodic oxidation and micro-arc oxidation.

Through scanning electron microscopy (SEM), wear test and corrosion resistance test, the surface morphology, oxide layer thickness, wear resistance and corrosion resistance of aluminum alloy are studied. The surface treatment has been analyzed and compared in detail.

The results show that: the surface of the surface treated aluminum CNC machined parts can form oxide films of different thicknesses, the surface hardness and wear resistance are obviously improved, and the corrosion resistance is also improved to different degrees. In terms of overall performance, micro-arc oxidation is better than anodic oxidation, and anodic oxidation is better than chemical oxidation.

1. Aluminum Phosphide

Using SEM, XRD, potential-time curve, film weight change and other methods, the effects of accelerators, fluorides, Mn2+, Ni2+, Zn2+, PO4 and Fe2+ on the aluminum phosphating process were studied in detail. Studies have shown that guanidine nitrate has the characteristics of good water solubility, low dosage and fast film formation. Fluoride can promote the formation of phosphating film, increase the weight of the film, and refine the grain; Mn2+, Ni2+ can obviously refine the phosphate film, make the phosphate film uniform and dense, and improve the appearance of the phosphate film. When the Zn2+ concentration is low , No film formation or poor film formation. As the concentration of Zn2+ increases, the quality of the film increases, and the content of PO4 has a greater impact on the phosphating film, and the content of PO4 increases. This content increases the weight of the phosphating film.

2. Alkaline electrolytic polishing process of aluminum

The alkaline polishing solution system was studied, and the effects of corrosion inhibitors, viscosity agents, etc. on the polishing effect were compared, and an alkaline solution system with good polishing effects was successfully obtained. ability. It is an additive that can not only increase the life span but also improve the polishing effect. The experimental results show that adding appropriate additives to the NaOH solution can produce a good polishing effect.

Exploratory experiments also found that under certain conditions, after DC constant voltage electrolytic polishing with glucose NaOH solution, the reflectivity of the aluminum CNC machined parts surface can reach 90%, but due to the unstable factors in the experiment, further research is needed. . The feasibility of using DC pulse electrolytic polishing method to polish aluminum under alkaline conditions was discussed. The results show that the pulse electropolishing method can achieve the leveling effect of DC constant voltage electropolishing, but the leveling speed is slower.

3. Environmentally friendly chemical polishing of aluminum and aluminum alloys

Decided to develop a new environmentally friendly chemical polishing technology based on phosphoric acid-sulfuric acid. This technology must achieve zero emission of NOx and overcome the quality defects of similar technologies in the past. The key to the new technology is to add some compounds with special effects to the base fluid to replace nitric acid. Therefore, it is necessary to analyze the three-acid chemical polishing process of aluminum, especially the effect of nitric acid. The main function of nitric acid in aluminum chemical polishing is to inhibit pitting corrosion and improve polishing whiteness. Combined with the simple phosphoric acid-sulfuric acid chemical polishing test, it is believed that the special substances added to the phosphoric acid-sulfuric acid should be able to inhibit pitting corrosion and slow down the overall corrosion, and it must have a better leveling and brightening effect.

4. Electrochemical surface strengthening treatment of aluminum and its alloys

The process, performance, morphology, composition and structure of ceramic-like amorphous composite conversion coating formed by anodic oxidation and deposition of aluminum and its alloys in a neutral system were preliminarily discussed.

Process research results show that in the Na2WO4 neutral mixing system, the concentration of the film-forming accelerator is controlled between 2.5 and 3.0 g/l.

The concentration of the complexing film agent is 1.5~3.0g/l, the concentration of Na_2WO_4 is 0.5~0.8g/l, and the peak current density is 6~12A/dm2. Weak agitation can obtain a complete, uniform and good-gloss gray inorganic non-metallic film. Floor. The thickness of the film is 5-10μm, the microhardness is 300-540 HV, and the corrosion resistance is excellent. The utility model has good adaptability to aluminum alloys, and can form a good film layer on various aluminum alloys such as rust-proof aluminum, forged aluminum and the like.

Aluminum alloy is the most widely used non-ferrous metal structural material in various industries. It has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industries.

With the rapid development of the industry, the demand for aluminum alloy welding structural parts for new energy vehicles and precision medical equipment is increasing, which makes aluminum alloy processing factories continue to deepen the research on aluminum alloy welding and processing.

After the aluminum CNC machined parts are laminated (anti-scratch), what method can be used to easily tear off the film?

Use acidic liquids such as dilute hydrochloric acid and toilet cleaner to clean the corroded area to make it fall off. Note that the concentration should not be too high, and the liquid should not get on the aluminum CNC machined parts.