[China Aluminum Industry Network] Abstract: Brief introduction to the production process of pearl black aluminum alloy aluminum profiles. Combining with practical aspects such as extrusion, oxidation and electrophoretic coating processes, the technological conditions for the production process to improve and stabilize the product quality are discussed.
Key words: aluminum profile; pearl black; electrophoretic coating; process control. Briefinducedtheproductionprocess
Ofthepearlyblackaluminiumprofiles
LUOShi-wei, ZHANGYi-fa, XIONGjian-qing, RUGUlong
(GuangdongJianmeiAluminiumprofileFactoryCO.,LTD.,Foshan,528231,Guangdong,China)
Abstract: Simply introduced theproductiveprocessofthepearlyblackaluminiumprofilesanddisgussedtheprocesscontrolfromtheextrusion,oxidation,electrophoreticcoatingtechnologytoimproveandstablethequalityofproducts.
Keywords:Aluminium profiles;Pearlyblack;Electrophoreticcoating;Processcontrol
1. Introduction With the increasingly fierce competition in the market, users are increasingly demanding the types and quality of aluminum products, making aluminum processing companies continue to innovate in product categories. Among them, the pearl black aluminum products are coated with a transparent electrophoretic paint on the surface of pure black aluminum products, so that it has a bright black pearl, so it is favored by all users, and the process control of pearl black aluminum profiles More difficult to control the production of Champagne and bronze color than usual, mainly reflected in the production of color red, gray, oxide film peeling, paint film surface dull or spots and other defects, can not meet the needs of users. This article gives a brief introduction to the successful production process technology control of pearl black aluminum profiles, for the same expert to start a role as a primer.
2. Production process of pearl black aluminum profiles The raw material for pearl black aluminum profiles is aluminum profiles after artificial aging treatment after extrusion. In the pretreatment, AC acid degreasers are used for degreasing, caustic washing, and sulfuric acid neutralization. Aluminum oxide coloring treatment, the use of sulfuric acid anode oxidation and single nickel salt electrolytic coloring. Its production process is shown in Figure 1.
Fig.1 Pearl Black Aluminum Production Process Fig.1Theengineeringflowsheetofthepearlyblackaluminiumprofiles
3. Production Process Control 3.1 Alloy Chemical Composition Control The influence of the material of the extruded profile on coloring has been clearly revealed in the production of bronze aluminum profiles. Excessive amounts of miscellaneous aluminum can easily lead to the technical quality of the profile bronzed green, gray, and matt. problem. Therefore, in order to improve the quality of the pearl black aluminum alloy profile, the alloy composition of the extruded profile must be strictly controlled, and the main chemical composition of commonly used 6063 aluminum alloy is shown in Table 1.
Table 1 The main chemical composition of the alloy control table Table1 Thecontrolofthealloyingelement
3.2 Extrusion process control For the 6063 aluminum alloy profile, the heat treatment technology commonly used at home and abroad is air-cooled and quenched on the discharge table of the extruder, so the extrusion die temperature must reach the quenching temperature, so that the Mg2Si strengthening phase is completely Solid solution. If the temperature is too low, solid solution will not be formed. If the temperature is too high, coarse grain structure will form. Especially when the outlet temperature exceeds 595°C, the material may be overheated and the Mg2Si phase may be enriched and precipitated, thus causing the profile to be formed during anodization. The Mg2Si is trapped in the oxide film and is gray. At the same time, coarse recrystallized structures tend to form, and the color is dull. Therefore, the preferred extrusion die temperature should be controlled at 515 ~ 530 °C.
3.3 Pretreatment process conditions Pretreatment mainly refers to the four processes of degreasing, caustic washing, neutralization and water washing. The purpose of surface pretreatment is to remove the oil stain and natural oxide film on the surface of aluminum profiles. In the pre-treatment process, degreasing should be clean, if the degreasing is not complete, prone to spots. Alkali washing is a key step in the pretreatment process. Alkaline detergents and additives, reaction temperature and time affect the surface gloss quality of aluminum profiles to varying degrees. The main process parameters are shown in Table 2.
Table 2 Pretreatment process parameters Table2Thetechnologicalparameterofthepretreatment
Under the conditions of the technical parameters in Table 2, the main features of pretreatment are:
(1) Excess corrosion will not occur if the corrosion time is extended to 2 times the new bath;
(2) Excess corrosion will not occur if the corrosion time is extended to 2 times the new bath;
(3) The smoothness of the corroded profiles is better than when the aluminum ion content is higher;
(4) alkali etching temperature should not be higher than 6O °C, time control in 2 ~ 4min.
3.4 Oxidation Process Conditions 3.4.1 Anodic Oxidation Loss of Light The visual black depth of the black appearance is strongly related to the brightness of the surface. The brighter the material, the more the appearance becomes pure black. For a pure black profile, the anodizing current density should be controlled. Under the condition of sulfuric acid mass concentration of 165-185 g/L, the current density should be 120-140 A/°. The greater the current density, the more serious the loss of light, and the smaller the porosity of the oxide film, is not conducive to the electrodeposition of colored particles in the subsequent process.
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1. The hardness of the material is moderate, and the tool wear of the machining equipment and CNC machining center is small.
2. It can be precisely machined into various geometric shapes such as plane, cavity, shell, sphere, arc, and anisotropy.
3. It is not easy to stain and maintain. Aluminum precision parts, precision parts processing, CNC processing
4. It has good durability and is not easy to corrode. With special treatment process, the service life of parts is longer.
5. Aluminum is environmentally friendly and can be 100% recycled, with high recycling value.
The above five points are the material characteristics of aluminum products. Aluminum is a common material in CNC precision parts processing, with moderate hardness, durability and corrosion resistance. In addition, the cost of materials is appropriate. It is the preferred material for most parts manufacturers.
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