Since the emergence of powder coatings in the early 1970s, powder coatings have received widespread attention worldwide due to their complete absence of toxic gases, ability to be fully converted into coatings, high efficiency, and good comprehensive performance in protection and decoration, resulting in rapid development. Metal profiles are widely used in various aspects of buildings due to their excellent durability, decorative properties, and processing formability. Aluminum profiles, on the other hand, account for more than 80% of metal profiles due to their excellent processing performance, light weight, and other characteristics. The application of powder coatings in aluminum profiles has grown rapidly. Currently, the application of powder coatings in aluminum profiles has expanded from Europe to the Americas, Australia, the Far East, the Middle East, and Africa. Currently, the surface treatment methods of aluminum profiles are generally used. There are three treatment methods: anodizing and powder coating, Each method has its own advantages and occupies a considerable market share. In the coating of aluminum profiles, representative types of powder coatings include outdoor, indoor, and anti-corrosion powder coatings. As applications, for some high-performance aluminum profiles such as aluminum frames, balconies, corridors, and partition panels, polyester outdoor powder coatings are mostly used. In addition, due to the excellent adhesion and anti-corrosion properties of powder coatings, but poor weather resistance, some are used as primers for indoor profiles

(1) The processing technology is relatively simple. Micro control can already be achieved for some key technical parameters, effectively reducing the difficulty of process operations, while greatly reducing auxiliary equipment, such as ventilation facilities, heating and freezing devices;

(2) The pollution level of water and air has been reduced, and alkali, sulfuric acid, and other liquid organic solvents are no longer used, reducing water and air pollution. It also effectively improves the competitiveness of aluminum profiles and plastic steel profiles as environmentally friendly products, and correspondingly reduces some production costs;

(3) The surface quality requirements for raw materials have been significantly reduced, and powder coating can completely cover the extrusion lines on the surface of profiles, masking some defects on the surface of aluminum profiles and improving the surface quality of finished aluminum profiles;

When powder coating is combined with technology to make profiles more fashionable, powder coating profiles have greater development space.

Two points to note before the production process of powder coated profiles

1. Fixtures: Fixtures can be divided into two types as a whole. One is the fixture placed at both ends of the profile, and the other is the fixture placed in the middle of the profile. The two have significant differences in application. The fixtures hung at both ends should be able to withstand a considerable amount of pressure, as a series like connection method is used in the feeding method. Due to the influence of the self weight of the profile and the small contact area between the hanger and the profile, the hanger must maintain a considerable load-bearing capacity; The fixture used in the middle part should follow a basic principle in the production and use process, which is to minimize the size of the contact points between the fixture and the outer surface (i.e. surface) of the profile as much as possible. The contact points hinder the adsorption of powder on the surface of the profile, forming some small defects; The larger the contact point, the larger the area of the defect, so the contact area of the fixture profile should be minimized as much as possible. In addition, the fixture in the middle part has a vertically placed hanging rod in the design, which absorbs some powder during the production process, hindering the adsorption of powder on the subsequent profile. Therefore, timely powder replenishment should be carried out for these parts.

The hanging position of the profile hanging fixture should also follow the corresponding principles, including placing the complex surface in a horizontal position as much as possible. The left and right sides of the horizontal surface are the places where the powder is most easily adsorbed, and the most complex side should be inclined towards the same direction as much as possible. At this time, the powder output and compressed air pressure of the inclined side can be appropriately increased, and the powder spraying direction should be parallel to the groove, making it easier for the powder to be adsorbed. For some profiles with deep grooves. Increasing the powder output and pushing the distance between the spray gun and the profile are both applicable. Surfaces with large surface area or complex structure should not be placed in a downward position, and decorative and non decorative surfaces of profiles should also be distinguished. In general, consumers often have higher requirements for decorative surfaces of profiles than for non decorative surfaces, and the bite between the profile and the wall can conceal some defects. For some special shaped profiles, adjust the position of the fixture in a timely manner to maintain a certain inclination angle of the profile at the hanging fixture position, in order to enhance the smoothness of operation and facilitate powder adsorption. In addition, for some heavy profiles, when using the fixture in the middle position, the elbow part should have a certain curvature, because when the weight is large, it will produce a phenomenon similar to curling tail, which is easy to fall off during operation. The curvature of the fixture can ensure that the profile is in a vertical position, ensuring a smooth production process. In addition, as the number of cycles of use increases, the coating on conductive beams and hangers will accumulate more and more. The coating itself is non-conductive and can affect the conductivity of conductive beams and hangers, thereby affecting the uniform distribution of powder on the surface of the profile. The coating on conductive beams and hangers should be removed in an appropriate manner. Pre processing: mainly for degreasing and tanning, with low raw material consumption, making daily maintenance relatively easy. What we should pay attention to in the pre-processing process. In order to improve production efficiency and reduce energy consumption during the drying process, relatively large material racks are often used in the pre-treatment process to load as many profiles as possible. The gap and density between profiles are the first considerations in the pre-treatment process. For some profiles with softer texture, more horizontal bars should be placed in the middle of the profile, and the groove should be placed as downwards as possible, which is beneficial for the evaporation of water. When there is still residual moisture after the drying process is completed, in order to avoid damaging the surface of the profile and preventing deformation of the profile when the temperature is too high, it should not be put back into the oven for baking. Cold drying or air gun drying can be used. In addition, the profiles must maintain an appropriate tilt angle when entering and exiting each groove and during the dripping process, but it is easy to cause some profiles to slip off. Therefore, a thousand pieces of steel wire mesh should be tied at one end of the material rack as a preventive measure.

Attention should be paid to issues in the spray booth.

(1) The position of the spray gun,

(2) The control of fluidized pressure, the function of fluidized bed is to use the action of airflow to form an appropriate fluidized state of powder, which feels similar to the state of liquid flow. The simplest operation is to detect that the fluidization has reached a sufficient state. When stirring the powder with hands or sticks, no resistance is felt. Fluidization facilitates the inhalation of powder into the duct, and under the action of accelerating wind, produces atomization effect. Insufficient or excessive pressure can cause fluidization failure

(3) The sealing inside the spray booth makes the powder easily contaminated by suspended particles in the outside air. After spraying, the surface of the profile is prone to produce flocs or shrinkage holes, which affect the flatness of the profile surface after baking. Therefore, the spray booth should take sealing measures to prevent the invasion of pollutants.

(3) A spare powder bucket for use during powder exchange can effectively improve labor efficiency. Maintenance work such as dust and moisture prevention must be done well to ensure the quality of the remaining powder in the powder bucket,

(4) In addition, the work of powder replenishment should also be taken seriously. Although various technical parameters have been debugged before normal production, the profiles should be continuously replenished through the powder replenishment window. If the powder is shallow or not adsorbed, it should be replenished in a timely manner. Due to the larger powder output of manual friction guns compared to automatic guns, the swinging speed of manual friction guns can be appropriately increased by hand. In addition, due to the influence of their own structure, some profiles may have blind spots during the powder coating process, and even with powder supplementation, normal effects cannot be achieved. These positions should be distinguished and powder supplementation should not be blindly carried out, otherwise there will be too much powder and thick coating, which will affect the surface quality of the profile and waste the powder. This type of position is mostly located on profiles with deep grooves and narrow widths. These grooves are mostly located on the non decorative surface of the profile. The overall appearance of the profile is not greatly affected, because the two opposing sides in the groove are at the same pole and too close to each other, forming a mutually repulsive electric field, known as Faraday shielding effect, which hinders the adsorption of powder inside the groove.

(5) The powder spraying production process is prone to powder pollution, which poses a threat to the health of operators, especially those in the spraying room. Therefore, it is necessary to strengthen labor protection work and take necessary preventive measures.

Powder coating is an important trend in the development of aluminum profiles at present. Many processes in powder coating production also have many areas that need improvement. Manufacturers are required to continuously modify existing processes to improve the surface treatment level of domestic aluminum profiles, promote the development of the aluminum profile industry towards renewal, depth, and higher direction, and meet the requirements of consumers for higher living standards.