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The so-called anodizing of aluminum is an electrolytic anodizing process in which the surface of aluminum and aluminum alloys is usually converted into an oxide film, which has protective, decorative and some other functional properties. The anodizing of aluminum starting from this definition only includes the process of forming anodic oxide film.

The metal or alloy parts are used as the anode, and the oxide film is formed on the surface by electrolysis. The metal oxide film changes the surface state and properties, such as surface coloring, improves corrosion resistance, enhances wear resistance and hardness, and protects the metal surface. For example, aluminum anodizing, aluminum and its alloys are placed in the corresponding electrolyte (such as sulfuric acid, chromic acid, oxalic acid, etc.) as the anode, and electrolysis is carried out under specific conditions and external current. The aluminum or its alloys of the anode are oxidized, and a thin layer of aluminum oxide is formed on the surface, the thickness of which is 5-30 microns, and the hard anodic oxide film can reach 25-150 microns. Anodized aluminum or its alloys improve its hardness and wear resistance, up to 250-500 kg/mm2, good heat resistance, hard anodized film melting point up to 2320K, excellent insulation, impact resistance The breakdown voltage is as high as 2000V, which enhances the corrosion resistance and does not corrode for thousands of hours in ω=0.03NaCl salt spray. There are a large number of micropores in the oxide film thin layer, which can absorb various lubricants, and is suitable for manufacturing engine cylinders or other wear-resistant parts; the film micropores have strong adsorption capacity and can be colored into various beautiful and bright colors. Nonferrous metals or their alloys (such as aluminum, magnesium and their alloys, etc.) can be anodized. This method is widely used in mechanical parts, aircraft and auto parts, precision instruments and radio equipment, daily necessities and architectural decoration. [1]

Generally speaking, the anode is made of aluminum or aluminum alloy as the anode, and the cathode is the lead plate. Put the aluminum and the lead plate together in the aqueous solution, which contains sulfuric acid, oxalic acid, chromic acid, etc. form an oxide film on the surface. Of these acids, the most widespread is anodizing with sulfuric acid.

(1) Pretreatment. The surface pretreatment process is generally degreasing and chemical conversion. Degreasing is generally treated with special degreasing agents, whose purpose is to remove the grease, dirt and debris attached to the surface of the aluminum profile during the extrusion process, and to remove the oxide film on the surface of the profile. Chemical conversion treatment is generally chromified or phosphorus-chromified treatment, the purpose of which is to form a layer of chemical conversion film (such as chromified film or phosphorus-chromified film) on the surface of the substrate to enhance the adhesion between the substrate and the coating, and to protect the substrate.

(2) Drying treatment. The purpose of drying is to remove the water carried by the pretreatment process. There are generally two ways of drying, one is natural drying, and the other is high temperature drying. Natural drying, long drying time, low efficiency, enterprises rarely use; Most enterprises are using high temperature drying. High temperature drying should control the drying temperature, the general drying temperature after chrome treatment should not be higher than 65℃. The drying temperature of phosphate-chromium treatment should not be higher than 85 ° C. If the temperature is too high, the chemical conversion film will lose too much water and be destroyed.

(3) Powder coating treatment.
Electrostatic powder treatment
Electrostatic powder treatment is applied the powder to the surface of the aluminum alloy profile through the powder spraying gun to form a protective and decorative organic polymer film. It is to apply negative high pressure to the spray gun and ground the workpiece to form a high voltage electrostatic field between the spray gun and the workpiece.
Electrostatic liquid spraying process
Electrostatic liquid spraying process is to apply liquid coating to the surface of aluminum alloy profiles by electrostatic spraying gun to form a protective and decorative organic polymer film. For acrylic paint spraying and polyester paint spraying, it is generally brush coating, that is, to form a layer of paint film, and fluorocarbon paint spraying generally requires two, three or four coating treatments.

What is the difference between electrophoresis and anodized?

The same point: all use electricity to complete the processing technology.

The difference: there is not much difference in appearance, but the texture is different. Anodizing is oxidized first and then colored, while electrophoresis is directly colored. The two are originally different processes. Anodized is a functional surface treatment with additional coloring, generally mainly on aluminum. On the other hand, electrophoresis focuses on decorative performance, but it is paint after all, and the metallic feeling may not be so good. Electrophoresis is equivalent to applying a layer of resin paint to the metal surface. And anodized is to use electrochemical method to make the surface metal aluminum and oxygen react to form a protective film, the surface has a metallic texture, and the grade is higher. It will be better if the electrophoresis is performed after oxidation.

anodized: anodized, the electrochemical oxidation of a metal or alloy. Aluminum and its alloys are a process in which an oxide film is formed on an aluminum product (anode) under the action of an applied current under the corresponding electrolyte and specific process conditions. Anodizing, if not otherwise specified, usually refers to sulfuric acid anodizing. In order to overcome the defects of aluminum alloy surface hardness, wear resistance, etc., expand the scope of application, and prolong the service life, surface treatment technology has become an indispensable part of the use of aluminum alloys, and anodized technology is currently the most widely used and most successful. of.

Electrophoresis: Under the action of an electric field, charged particles move toward the electrode opposite to it, which is called electrophoresis (EP). The technique of using charged particles to move at different speeds in an electric field to achieve separation is called electrophoresis.

The industrial aluminum profile is an industrial frame profile produced by heating the aluminum rod through the extrusion mold. And the aluminum rod is melted through the aluminum ingots, which is called the industrial aluminum profile raw materials; The quality of raw materials will directly affect the performance of industrial aluminum products.

We should control the temperature when do the heating treatment of aluminum rod. If the temperature is too high or too low, it will directly affect the hardness of the finished product. So the temperature must be strictly controlled during the heating and cooling process.

Industrial aluminum profile is the final product of aluminum rod extruded by heating through the molds, and the molds are designed according to the demand with high precision specifications, used for extruding the required profile products.

The speed of extrusion is a fundamental and critical process factor for production, it must be carefully controlled during the extrusion process.

The straightness affects the use of aluminum profiles, so the straightness of aluminum profiles is one of the important standards for the quality of aluminum profiles. Generally, the extruded profiles need to be straightened for ensuring the straightness.
When the aluminum profiles are extruded from the machine, them have low hardness before aging and cannot be used as finished products. So in general, they must be aged to improve strength.
In addition, To increase its hardness, for the T5, we usually let the aluminum profile cooling by air; For the T6, we normally cooling it by water.

Generally the surface of aluminum industrial profiles is anodized silver, with this treatment, the profiles will be elegant, beautiful and corrosion resistance. Then after cooling, straighten and cutting, the aluminum extrusion part complete.

In order to ensure that the technical requirements of exterior doors and windows are clarified in the process of project design, procurement, and construction, the performance requirements of wind pressure resistance, water tightness, air tightness, heat preservation, sound insulation, lighting, safety, etc. are met, and common problems in exterior doors and windows projects are avoided. Repeatedly, these ten key points of door and window quality control are worth seeing! These are the quality inspection points when the broken bridge aluminum doors and windows project is completed.

Front part: Quality control performance requirements for exterior doors and windows

1. Carefully choose the color of aluminum alloy doors and windows.

Mainly divided into two kinds of monochrome and wood grain color. General monochrome such as white, gray, wood grain color such as North American oak, South Asian rosewood, camphor wood, sandalwood, red sandalwood. In terms of the color of the paint surface, the color of the aluminum door needs to be combined with the decoration style and design of your home, so as to perfectly combine the harmonious atmosphere.

2. Choose aluminum alloy doors and windows made of healthy and environmentally friendly materials

During the purchasing process, you will definitely smell the smell from the doors and windows. Doors and windows made of inferior materials can damage the respiratory tract, leading to dizziness and headaches. High-quality aluminum alloy doors are made of high-quality, healthy and environmentally friendly aluminum profiles. The smell is light, and it usually doesn’t smell after a while.

3. Door and window details matter

Doors and windows with good details are equivalent to appreciating a carefully crafted handicraft. Its connection, colloid bonding, and extrusion processes are all products processed through multiple links and multiple processes. The treatment of details is related to the beauty and life of doors and windows. When purchasing, you must carefully inquire, select, and read the product manual to understand the forming process.

4. Focus on texture

Aluminum alloy doors and windows are the patron saint of a home. The quality is good or bad is to determine the value of a door and window. At the time of purchase, you can judge whether it is rough, cracked, or poorly colored by touching it. Regular brand aluminum alloy doors and windows, the manufacturer, place of origin, model, specification, etc. will be written on the label. Beware of buying counterfeit and inferior products.

The spray guns should maintain a certain inclination, which is biased towards the running direction of the profile. The spray guns should be kept vertically parallel in arrangement, and the end parts should be kept in a straight line. There should be no overlapping parts between the spray guns. It is advisable to cover all profiles.
Control of fluidizing air pressure
The control of fluidized air pressure, the function of the fluidized bed is to use the effect of the air flow to make the powder form a proper fluidized state, the hand feel is similar to the state of liquid flow, and the fluidization is detected to reach a sufficient state. The simpler operation is: use When the powder is stirred by hand or stick, there is no resistance. Fluidization facilitates the suction of powder into the duct. Under the action of accelerated wind, the effect of atomization is produced. Insufficient or excessive pressure will cause insufficient fluidization.