Defects and Solutions of Powder Coating on Aluminum Profile
Firstly: Color Difference
Causes of defects:
1. Uneven coating thickness of aluminum profiles;
2. Not uniform temperature distribution of the aging oven;
3. Simultaneous production of goods with different materials, thicknesses, shapes and sizes;
4. Before changing the powder paint, the powder feeding device, spray gun, spray room and powder recovery are not be cleaned;
5. Color difference caused by poor distribution of powder and paint.
Solutions:
1. Ensure that the thickness of the coating film on the aluminum profile is uniform;
2. The temperature distribution of the aging oven is uniform;
3. Classify the goods according to the material, thickness, shape and size；
4. Clean all materials and devices before changing the powder paint;
5. Improve the quality of the powder and ensure that the L, a, and b of the powder are not much different and their positive and negative are uniform.
The Future Trend of Green Environmental Protection by Replacing Wood with Aluminum —— All Aluminum Home Furnishings
Nowadays, more and more people accept the green and environmentally friendly light steel houses. And more and more light steel villas have become the first choice for many people. Meanwhile, the green and environmentally friendly all-aluminum homes are also favored by residents. Afterwards the popularity of light steel villas, why all-aluminum homes are also popular?
Basic Knowledge of Aluminum Profiles
Aluminum profiles can be classified according to their applications:
1. Industrial aluminum profiles: mainly used in airplanes, trains, industrial heat sink, automobiles, electrical appliances, etc.
2. Aluminum alloy building profiles: mainly used for building doors and windows, curtain walls, indoor and outdoor decoration and aluminum profiles for building structures.
Aluminum profiles can be divided by different surface treatments:
1. Anodized aluminum profile: the profile surface is anodized, electrolytically colored or organically colored.
2. Electrophoretic painted aluminum profile: the surface of the profile is treated by anodized together with electrophoretic painting.
3. Powder coating aluminum profile: the surface of the profile is coated with thermosetting organic polymer powder.
4. Fluorocarbon spraying aluminum profile: the surface of the profile is coated with polyvinylidene fluoride paint. At present, the commonly used heat-insulating profile is an aluminum alloy profile that is threaded or poured.
INTOP ALUMIUM FACTORY
Now please allow me to make a brief introduction to our company and products.
We Intop Metal factory established in 2015, is located at Tian’an centre, Jihua Dong Road, Nanhai District, Foshan City, Guangdong Province, China, covering an area of 60,000 square meters, of which there are not less than 300 workers. Production equipment is the hard power for manufacturers. We have introduced lots of advanced production lines in our workshops, for example, 3 sets of casting ovens, 2 sets of aging ovens, 10 sets of extrusion lines, 1 set of horizontal anodizing line, 2 sets of powder coating line, one for vertical and the other for horizontal, and 2 sets of transfer wood grain lines.
Aluminum extruded profiles
Aluminum profiles are extruded sections of aluminum that have a variety of cross sectional shapes. They are commonly used in construction, manufacturing, and engineering industries due to their lightweight, corrosion resistant, and high strength properties.
INTOP METAL ALUMINUM factory in FOSHAN GUANGDONG
Our factory is located in Nanhai District Foshan City, which is one of the most professional gathering places for aluminum profiles in China. You can find many factories of aluminum profiles in Nanhai, but our factory is highly competitive in aluminum profiles in this industry. We have complete advanced production lines as below: 12 extrusion lines, 2 powder coating lines, 2 anodizing line, 2 transfer wood grain line, 1 mechanical polishing production line, 3 sandblasting production lines. We are a large-scale manufacturer of aluminum profiles for windows and doors and aluminum industrial profiles, covering 80,000 square meters, with annual output up to 38,000 tons.
INTOP METAL ALUMINUM factory in FOSHAN GUANGDONG
Welcome to our INTOP METAL ALUMINUM factory in FOSHAN GUANGZHOU!
When you want to get your lovely extrusion profiles:
Firstly, we need the CAD drawings and samples of your aluminum profiles for reference. We need CAD drawings that we can see the size of your industrial profiles exactly; But if you can send us some piece of your aluminum section products, we can make the aluminum profiles CAD drawings free for you and produce perfectly the same profiles as your requirement.
INTOP METAL ALUMINUM factory in FOSHAN GUANGDONG
At the loading platform, we load the goods into containers here.
The first room we enter is our warehouse. After production, your goods will be packed and stored here. As you can see, so many aluminum profiles for our customers are stored here. We have large production capacity. We manufacture at least 25,000 tons each month.
And this is the packing workshop. Before loading, the aluminum profiles need to be packed for protection. We lay the aluminum profile on the packing table and stick with protective film. And then we put on the “heat shrink”.
This is the vertical line for powder coating. As you can see, we lay the aluminum profiles on the equipment. We hang on the profile through its small hole on the top. And the worker who is in charge of the vertical line will hang the profiles one by one. After hanging finished, the profiles will be slowly transported by the machine to the end of the vertical line — “the coating room”. In the coating house, the aluminium will be sprayed with beautiful surface as you like.
This is the transfer wood grain workshop. There are two work lines for production. Let me introduce the steps for wood grain. At first, we will let the profiles coat the background color as you request, and wrap it with transfer paper then put it in a plastic sleeve. After these steps, we will drain the air of the plastic sleeves to let the transfer paper stick firmly with the profiles. The last step, we put the profiles in the oven under the temperature around 180℃ for 30minutes. These are the main steps for wood grain.
This is the warehouse of our moulds. Before production, we will make the moulds and they have to be checked and confirmed by the customers. Many types of molds of our customers are stored here.
This is the anodized workshop. On the top is the anodized, washing and electrophoresis tanks. We fixed the profiles below, and then the machine will take them to the tanks for washing, cleaning, anodizing or electrophoresis.
These two machines are for sand blasting. This one for steel blasting, and the other one for glass blasting.
This equipment is the polishing machine. Our polishing machine is high-end and in high quality. It can perfectly produce polished surface.
This is our horizontal line for powder coating. Different from the vertical line, they won’t have small hole on the head. The profiles on horizontal line are fixed by small metal clamps, there is a mark cased by metal clamps or fixed line.
This is our melting workshop. There are five equipment. All ingots in our factory are pure, and the aluminum rods are melt without any scrap material to ensure the quality.
This is our extrusion workshop. There are 11 extrusion lines in total. We put the aluminum profile molds into the extrusion machine, and put the aluminum bar in hot shear to cut into small pieces. Then we’re going to push these small pieces into the extruder through the mold and form into the shape as you request.
This is our aging workshop. There are two aging ovens. When the profiles are extruded out, we need to put them into the aging oven to increase their hardness.
Now we have finished visiting all the workshops of our factory. Let’s back to our office and take a break.
Aluminum anodizing treatment technology
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.
Aluminum profile Powder coating process
(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.
