Case of Post – Treatment of Aluminum Profiles: Creating Colorful, Aesthetically Pleasing and Durable Door and Window Frame Profiles
I. Project Background
A building decoration enterprise undertakes a door and window project for a high – end commercial building and needs to customize a batch of aluminum profiles as door and window frames. These aluminum profiles not only need to have basic properties such as high strength and weather resistance but also need to achieve a variety of surface post – treatments to present rich colors, enhance the overall aesthetics of the building, and meet the designer’s creative needs for the appearance of modern buildings. Therefore, CNC machining combined with multiple post – treatment processes is adopted.
II. Requirement Analysis
(I) Material Performance
The 6063 – T5 aluminum alloy profile is selected. It needs to ensure strength and hardness to meet the load – bearing and wind – pressure resistance requirements of the door and window frames. At the same time, it should have good machinability and corrosion resistance to adapt to the subsequent surface treatment processes.
(II) Dimensional Accuracy
The length tolerance of the profile is controlled within ±0.5mm, and the cross – sectional dimension tolerance (such as width and thickness) is ±0.2mm to ensure accurate adaptation to door and window hardware and guarantee the installation stability and sealing performance.
(III) Surface Post – Treatment
It is necessary to achieve uniform and long – lasting adhesion of a variety of colors (green, white, black, orange, blue). The surface should be smooth and free of defects, and have properties such as scratch resistance, UV resistance, and rain erosion resistance, so as to maintain an aesthetic appearance for a long time.
III. Production Process
(I) Pre – CNC Machining
- Profile Cutting: According to the design dimensions of the doors and windows, use CNC cutting equipment to cut the 6063 – T5 aluminum alloy profile into the specified length. The cutting surface is flat and smooth, without burrs and edge chipping, and the tolerance is controlled within ±0.3mm, laying a foundation for subsequent processing.
- Precision Milling: For the connection parts, installation notches and other structures of the profile, use the CNC milling process to mill out 卡槽 (card slots) and 榫头 (tenons) with precise dimensions to ensure perfect fitting with other components during subsequent assembly. The milling accuracy reaches ±0.1mm, ensuring the assembly accuracy of the door and window frames.
(II) Key Links of Surface Post – Treatment
- Pretreatment: Sequentially carry out processes such as degreasing (removing oil stains on the profile surface), pickling (dissolving oxide scales and impurities), alkaline washing (neutralizing acidity and further removing impurities), water washing, and chromating (forming a chemical conversion film to enhance coating adhesion). Make the profile surface clean and with appropriate activity, preparing for subsequent coloring and spraying. Strictly control the time, temperature, and reagent concentration of each process to ensure uniform and consistent treatment effects.
- Coloring Treatment (for Different Color Requirements)
- Powder Spraying (for white, black, etc.): Ground the pretreated profile, use electrostatic spraying equipment to make the powder coating (such as polyester powder) adhere to the profile surface, then put it into a curing oven, and bake at 180 – 220°C for 15 – 20 minutes to form a uniform coating with a thickness of 60 – 100μm, with full color and strong adhesion.
- Anodic Oxidation Coloring (for green, orange, blue, etc.): Use the profile as the anode and put it into an electrolyte such as sulfuric acid, and pass direct current for anodic oxidation to form a porous aluminum oxide film. Then immerse it in a coloring solution containing metal salts (such as nickel salts, tin salts, etc.). Use the adsorbability of the porous film to make the dye molecules enter the pores to achieve color adhesion. Then perform a sealing treatment (hot water or nickel salt solution sealing) to close the pores, improve wear resistance and corrosion resistance, and make the color long – lasting and stable.
- Post – Treatment Inspection: For the profiles completed with surface treatment, use the cross – cut method to test the coating adhesion (adhesion grade ≤1 level), and use the salt spray test to detect corrosion resistance (no obvious corrosion and discoloration in the neutral salt spray test for 1000 hours). Visually inspect the surface color uniformity and check for defects such as flow marks and pinholes to ensure that the post – treatment quality meets the standards.
IV. Project Achievements
(I) Performance and Precision Guarantee
After CNC machining and post – treatment, the aluminum profiles have precise dimensions, meeting the assembly requirements of doors and windows. The 6063 – T5 aluminum alloy material combined with perfect surface treatment has excellent strength and weather resistance, ensuring the long – term stable use of the door and window frames.
(II) Color and Appearance Advantages
Achieve high – quality presentation of a variety of colors. The coating or oxide film is uniform and smooth, with bright and long – lasting colors, endowing the door and window frames of commercial buildings with a unique visual effect, conforming to the designer’s creativity and the overall style of the building, and enhancing the aesthetics and quality of the project.
(III) Market and Application Value
Help the building decoration enterprise successfully deliver the high – end door and window project. With the excellent post – treatment effect of aluminum profiles, enhance the market competitiveness of the project. Provide reliable aluminum profile processing and surface treatment solutions for subsequent similar building decoration projects, and promote the exploration of the application of personalized and high – quality aluminum profiles in the building decoration industry.
