Powder coating: what is it and where is it used? How to paint a car with powder paint.

The method of powder painting of metal products makes it possible to obtain a high-quality and durable decorative and protective powder coating.

Areas of use and advantages of powder technology

Powder coating of metal products is widely used industrial enterprises for reliable protection:

elements of various vehicles;
facing and roofing, as well as some other building materials;
equipment and units used in the chemical industry;
agricultural machines.

With the help of technology, a durable protective and decorative coating is formed on cars, electronic devices, various elements of modern architecture, home appliances.

The process is quite fast due to the fact that the coating hardens very quickly after applying the powder mixture to. At the same time, the part has to be dried only once, in contrast to cases when the products are treated with conventional paints and varnishes (they usually have to be applied 2–3 times to obtain the desired effect).

The painting technology, which we will discuss below, requires compact equipment that performs all planned operations as quickly and efficiently as possible. The powder coating itself does not contain solvents and guarantees the use of the material at the level of 96-98%.

The compositions are supplied to consumers in a completely ready-to-use form; there is no need to add additional ingredients to the powder paint and control their viscosity level. This ensures high quality painting and cost-effectiveness.

There are no flammable and toxic components in the coloring composition, it is environmentally friendly. Note that a small part of the powder that remains after painting (2–4%) can be reused in the technological process.

Other advantages of powder coating include high adhesion of the compositions used, the possibility of maximum automation of the process, the absence of wrinkling and streaks on the treated surface, low shrinkage and porosity of the paint due to the fact that it does not contain solvents. In addition, the powder coating is not afraid of high (up to +120 ° C) and low (up to -60 °) temperatures, guaranteeing a durable protective layer. Coated metal products are aesthetic, there are big choice color shades(more than 5000).

Powder coating technology - how does it work?

A high-quality decorative and protective coating on metal products with compositions in the form of a powder requires strict adherence to technological operations. First, the metal surface must be prepared for painting by thoroughly cleaning it from rust and old paint or powder layers by stripping them. In principle, the old coating can be left on, but then the material will not adhere well to the surface, which will lead to a decrease in the quality of the painting.

You also need to degrease the metal product, and then dry its surface. In some cases, the metal still needs to be additionally phosphated or chromated (if required by the operating conditions of the product).

These procedures are most often performed when powder coating parts of cars.

Next, the metal product is fed into the painting chamber on a special conveyor belt, on which the part is securely fixed. In the chamber, a powder of the selected color is applied to the part. It stays on the surface solely due to the fact that a certain potential difference forms between the paint and the metal surface.

In a separate polymerization department, polymer coating takes place - melting of the applied powder and subsequent hardening of the film. The result of the operation is the penetration of the coloring composition into the pores of the product to a great depth.

Then the metal product is kept in air for the time specified by the process in order to acquire the required strength and solidity. With a powder paint residue recovery unit, the part that has not been used can be recycled.

What equipment is used for powder coating?

Coloring is done in special rooms using production lines or compact units. The latter can be non-mechanized and mechanized. Compact units are used in service stations. Theoretically, you can use them even in an ordinary car garage.

If during the year the company paints about 50 thousand square meters. m. of metal products, it makes sense to use production lines, which are a chain of units and machines closed by a conveyor of periodic or continuous action. Such lines usually include the following cameras and devices:

spray chamber;
vibrating sieve (sifts the “secondary” powder material for painting coming from the recuperator);
paint sprayer;
recovery plant;
feeder;
drying compartment.

Spray chambers limit the area where powder paint is sprayed, preventing it from reaching other equipment or workers in the production area. They can be equipped with several or one post for performing work, they are walk-through and dead-end, mobile and stationary. The walls of such chambers are made of polypropylene impregnated with antistatic compounds, hard plastics, durable glass and various steel grades.

Spray compartments various manufacturers have their own design, characterized by:

features of the execution of the system for the selection of the coloring mixture from the bottom of the installation;
the location of the air suction mechanism in the chamber (from below or from above);
placement of working and transport compartments.

Sprayers (manual for small-scale production and stationary, built into an automatic cycle; according to the principle of operation - tribostatic and electrostatic) are necessary for applying a coloring material to a metal surface. Tribostatic devices have a lower productivity than electrostatic devices (10 kilograms of powder per hour versus 15–20). At the same time, both variants of sprayers are equally in demand by modern enterprises.

Powder coating equipment feeders are special ejectors in which air takes the required amount of paint to form an aero mixture with a given amount of solid elements. Subsequently, the resulting mixture goes to the sprayer through the hose, and then applied to the product.

Metal is one of the most sought-after materials for the production of products in various fields, but unlike plastics or natural materials having their own attractive color, the metal needs to be painted. Painting of metal products is necessary to give an aesthetic appearance and protection against corrosion of steel or cast iron.

Powder coating of metal is a monolithic coating adapted to different conditions operation. The resulting coating on metal products is resistant to salt environments and abrasives.

In industrial conditions, the use of paints and varnishes based on organic solvents is gradually being replaced by powder paints, as this technology has a number of advantages over the classic painting of metal products. Powder paint is a polymer powder that has different shades and properties. The catalog "Euro-Decor" presents certified products High Quality.

The use of painted metal products

Painting of metal products is in demand in industries where there is a need to give metal products an aesthetic appearance and protect against corrosion. Used for painting surfaces in contact with food, or located in residential premises. Aluminum radiators, household electrical appliances, including freezers and cold rooms, washing machines, as well as various interior items.

Coloring of hardware is also used for outdoor conditions. Types of painting adapted for service in conditions of constant atmospheric action are used. Constant fluctuations in temperature and humidity, as well as ultraviolet radiation, are not dangerous for a metal structure if the right, certified by the QUALICOAT system, powder paint is selected.

Powder materials can be used to paint any type of metal, made of non-ferrous and ferrous alloys, which makes them very popular. If the technology is followed, the appearance of air inclusions and, as a result, swelling of the surface, is completely excluded between the paint layer and the metal surface. This method of painting metal products has shown itself especially well in the cities of Russia, where there is always a damp climate that negatively affects the painted metal constructions and regular paint coatings that need to be updated regularly.

Compound

Metal painting is carried out with powder paints with different composition, but belonging to one of two groups, according to the technology of coating formation.

Thermoplastic mixtures - the coating is obtained due to the melting of the powder mass, followed by solidification. Resistant to water, weather and other factors, but has a reversible structure. The thickness of the painted layer is from 250 microns or more.
Thermoset mixtures - the formation of a three-dimensional structure occurs as a result of thermal action on the powder, but thermochemical reactions are the driving factor for formation. Painted metal has an irreversible structure and a small layer thickness - from 80 to 120 microns, resistant to solvents.

Coating features

Powder coating of metal products based on epoxy resins has high-quality characteristics in terms of mechanical stability and is characterized by good adhesion, however, it does not tolerate overheating, as a result of which it can acquire yellow. On hit ultraviolet radiation, the top layer begins to crumble like chalk. Suitable for painting metal products indoors.
This disadvantage is compensated in compositions with epoxy-polyester fillers, which have the ability to create polyester films on the surface. Thanks to this solution, it was possible to reduce the likelihood of yellowness and at the same time increase the temperature limit.

For the full-fledged outdoor operation of metal structures, polyester blends are produced, they are completely neutral to atmospheric effects and therefore do not collapse. To give the painted product high wear resistance, the metal is painted with polyurethane paints that are resistant to contact with mineral oils, solvents and liquid fuels.
It is possible to paint metal and metal products not only in Moscow, but also in any region of Russia, by contacting us or our representatives, you will receive information about companies providing services for painting metal and metal structures.

Painting of hardware

The basis for good adhesion and, accordingly, a long service life of a metal product coating is high-quality preparation for painting. The surface of the metal sheet or part is pre-washed with degreasing solutions, the final flush is carried out with specially prepared deionized water. The product is dried and the next step is finishing mechanical cleaning, with a layer of coloring powder applied.

Powder spraying on metal is carried out by two methods:

Spraying by electrostatic method - paint particles receive a charge, flying past a high-voltage electrode;
Spraying by tribostatic method - the paint is charged by friction against inner surface atomizer made of a special material (most often Teflon).

After melting, polymerization in a thermal chamber and cooling, the painted metal products are ready for use.

Caring for a painted product

Subsequent care of the metal product is carried out in accordance with the manufacturer's instructions, and if the operating mode complies with the recommendations in the instructions, then the service life of the coating significantly exceeds the guaranteed one.

Our company supplies expendable materials for powder coating to enterprises in Moscow, as well as to most regions of Russia, which makes it easy to find a contractor and be sure of the quality execution of the order.

Differences in the composition and technology of use, distinguish this type of coating into a "special class" relative to other paints and varnishes. At present, powder coating of metal products has become widespread in industry, ranging from aircraft construction to the production of household goods and accessories.

Powder coating of metal products: process technology and main stages

The technological process of powder coating is divided into the following stages:

preparation of the painted surface;
applying paint in powder form;
formation of a liquid film at high temperature;
chemical curing of the film-forming material (when using thermosetting paints);
final formation of the coating.

Surface preparation

When preparing the surface to be painted, it should be taken into account that it is necessary to ensure not only wettability with the liquid phase of the film former, but also a uniform distribution of powder materials during spraying. Attention is paid to both removing all kinds of surface contaminants and providing the surface with the necessary roughness. In addition to mechanical methods surface preparation can also be chemical, such as etching or phosphating.

Application of powder materials

Powder coating of metal is carried out:

electrostatic spraying;
immersion in a suspended layer of electrified powder;
gas flame method.

Due to its simplicity and versatility, the application of paint has received the greatest application. electrostatic spraying. For flat surfaces, special magnetic brush rollers can be used according to the technologies used in copying technology. Dipping in the "fluidized bed" used on automatic lines in the conveyor production of the same type of products. flame method due to the excessive unevenness of the layer and the properties of the resulting coating, it has not received distribution. Existing plasma spraying is distinguished by the use of low-temperature plasma to heat particles and the use of an inert gas; limited to the use of heat resistant powders in application thin coatings for heat resistant materials.

Retention and uniformity of distribution of powder materials on the surface of metal products are provided due to the electrostatic forces of the interaction of charged paint particles and the “electrically neutral” surface. Before spraying, the paint particles in the gun are electrically charged:

in the field of the coronary charge created by the electrode;
due to friction on the surface of the equipment.

The particle charge is usually negative, the charge value must correspond to the optimal range that allows particles to be kept on the surface until a liquid film is formed and does not violate the deposition technology. It is regulated by the characteristics of the electrode or the speed of movement of particles during friction against the surface of the equipment, by the area and material of the surface.

With electrostatic spraying, coatings are formed with the same quality on horizontal and vertical surfaces. The zero charge of a metal product is provided by grounding.

Liquid film formation

Film formation occurs when powder materials are heated to a viscous-fluid state, and the following occurs:

deformation and viscous flow of the material;
air removal;
wetting liquid material substrate surface.

in the production of pipes and metal profile powder is applied in a "fluidized bed" to preheated workpieces, the process of forming a liquid film occurs due to the accumulated heat or additional heating.

In the case of using thermosetting paints at high-temperature exposure, the chemical curing of the liquid film additionally occurs due to polymerization or polycondensation of film formers. This lengthens the high-temperature holding time, increases costs and reduces productivity. There are compositions based on thermosetting resins, the accelerated curing of the films of which occurs under ultraviolet irradiation.

Final coating formation

The final formation of the film occurs when the product is cooled. The conditions may differ both in the cooling rate and in the medium. Strength characteristics coatings and adhesion forces, depending on the conditions of formation, can vary by tens of percent. At the same time, for different types polymers, accelerated and delayed cooling is practiced. Coating cooling in plasticizing polymer environments can reduce internal stresses coverage to zero.

Unlike thermoset paints, thermoplastic paints make it easy to repair coating defects using re-sintering.

Powder coating is widely used in the construction industry in the production of profiles from steel and aluminum, the manufacture of doors, gates and other metal structures. In the automotive industry, it is used in the production of wheel rims and other parts.

Despite the complexity of tinting, some manufacturers provide powder paints up to 250 colors according to RAL tables.

The process of preparing metal parts for painting

When painting metal products with powder paint, both on industrial lines and with your own hands at home, you must follow these recommendations:

Use powder materials from trusted manufacturers.
Without proper grounding of a metal product, the electrostatic mechanism for holding and distributing powder materials on the surface is disrupted. Therefore, it is necessary to monitor the condition of the hanging hooks that provide grounding of the parts. Should provide technological operation cleaning hooks and monitoring the ground circuit.
Spraying of powder materials must be carried out to a minimum necessary quantity air. Excessive air supply leads to:

overspending paint;
increased wear of equipment;
violation of the technology of electrization of powder particles;
change in the granulometric composition of the paint;
poor visibility in the spray booth.

A high-quality coating is obtained by using air of the required condition. In this case, attention should be paid not only to the absence of dust, but also to the content of moisture and oil in the air. Appropriate filters must be used prior to supplying the air mixture to the equipment. In quality air:

the size of solid particles does not exceed 0.3 microns;
the dew point does not exceed 4 °C (i.e. at 20 °C humidity is not more than 35%);
oil content is not more than 0.1 ppm.

At reuse powder materials, the change in the initial composition, primarily the granulometric composition, is taken into account. The amount of allowed additions of regenerated materials to the original powders should not be exceeded. Thoroughly homogenize the powder mixture before use.
Do not mix paint of different colors and types. When changing to another paint, it is necessary to thoroughly clean all equipment. It is advisable to have separate supply hoppers and hoses for each paint used.
Without surface preparation, you will not get a quality coating. In this case, the purpose and operating conditions of the product should be taken into account. The frame of a bicycle must be prepared a little differently than the elements of an office desk. Careless preparation leads to:

surface defects of the coating;
peeling paint;
premature destruction of the coating in an aggressive environment.

The cost of the initial powder does not determine the real economy of the coating. Should be considered:

material consumption per unit surface area;
coating durability;
resistance to harmful conditions;
appearance.

Consider storage conditions for powder materials. Elevated temperature can reduce both the processing characteristics of the powder and the operational properties of the coating. The containers used must be waterproof due to the high hygroscopicity of the materials. Typically, the recommended temperature in the warehouse should not exceed 25 ... 28 ° C, humidity should not exceed 50%.
Strictly follow the recommended technology of "sintering" the powder. It should be noted that the air temperature in working area furnace is an indirect characteristic of the process. The operation of the installation should ensure uniform heating of the metal of the product to optimal temperatures. Depending on the type of material and weight of the product optimum temperature air and exposure time may vary and are reflected in the instructions.
Do it on time technical regulations to maintain the performance of site equipment. Preventive maintenance, including regular cleaning, inspection, repair and replacement of components, is the basis for flawless operation and quality products. Use spare parts from original manufacturers. TESLA equipment has proven itself well.

Safety

The main types of threats in the powder coating of products are.

Modern technologies for painting metal products are developing rapidly. The use of liquid paints is gradually receding into the background, and most of the manufacturers of steel or aluminum structures are increasingly giving their preference to powder products. Their use guarantees a better protective coating that can last for a long time.

Application areas of powder coatings

Powder paints are among the high-tech materials that have unique characteristics that are not characteristic of liquid coloring agents. Their composition consists of coloring pigments, catalysts and resins necessary to form a durable layer. Catalysts play the role of an accelerator for the hardening of the composition. Unlike liquid analogues, powder-based products do not contain a solvent, and air plays the role of a dispersion medium. This reduces their toxicity and significantly saves in their production.

The method of application of these materials is not suitable for all purposes. It has found application in cases where it is necessary to provide reliable protection against corrosion. In certain cases, this method will help to increase electrical insulation.

In industry, the application of such materials is used to:

painting of forged products, galvanized and aluminum profiles;
work with medical and laboratory equipment;
furniture manufacturing;
production of household appliances;

This method is also often used in the manufacturing process sports equipment. Often, well-known auto concerns apply the technology for applying such products.

Advantages and disadvantages of modern technology

There are many benefits to powder coating. First, as a result of work, a minimum of waste is generated. Work with the use of high-quality equipment is most effective.

Secondly, the work is carried out in the best sanitary and hygienic conditions. This technique is environmentally friendly. Even inside a specialized oven, which is used to cure paint, the amount of toxins does not exceed the maximum allowable rate,

Thirdly, solvents are not used during operation, due to which shrinkage is reduced, and there are practically no pores on the surface of painted metals.

The use of compounds is considered a fairly economical method of painting. It will take no more than 30 minutes for the layer to harden, resulting in a hard coating on the surface. Thanks to this, you do not need to apply additional layers of material, and during transportation you will spend less money on packaging.

The painted surface is highly resistant to sunlight and moisture. In addition, painted products are less susceptible to direct fire.

Among the minuses, the melting of powder paints at temperatures from 150 ° C stands out. Because of this, they cannot be painted with plastic and wood. Apply thin layer composition is problematic. It is important to remember that for the preparation and use of each shade, you will need to use separate containers. It is quite difficult to paint objects with such a coloring agent. non-standard shape. In addition, if scratches still form on the surface, then it will not be possible to remove them locally - you will need to paint a large area. There are no tinting agents in stores, so only standard factory colors can be used.

Classification of powder formulations

Depending on the type of film formed, powder compositions are divided into thermosetting and thermoplastic. In the first case, the coating is formed as a result of certain chemical reactions. In the second - powder coating of prepared metal objects is carried out under the condition of exposure to high temperature, without the participation of chemicals.

Thermosetting compounds are more popular. Epoxy, polyester and acrylic resins are used in their production. Their main advantage is that the painted surface will not melt or deform during secondary heating. This type of paint is suitable for working with items that are designed for use in extreme conditions.

In the manufacture of thermoplastic compounds, the role of resins is played by vinyls, nylons and polyesters. A hard coating is formed upon cooling and final hardening of the layer. When reheated, the paint will melt.

Common paint application methods

Powder coating of various metal products can be performed in several ways. The first of these is air spraying. To do this, the object to be processed should be heated, after which the particles are evenly distributed over its surface. To improve the quality, it is necessary to heat the object to be painted to the highest temperature possible at home.

Electrostatic treatment is the adhesion of material particles caused by electrostatic stress. At the end of the polymerization, the object must be left to dry naturally. This technology is well suited for painting small and simple objects.

The third method is based on the use of flame. For work, special pistols are used, which are equipped with a propane burner. In the process of application, the particles, passing through the flame, melt and fall on the surface of the product in a semi-liquid state. The surface of the product itself does not heat up. As a result of using this technology, the applied layer is uniform and thin. This method is used exclusively for painting large items.

Painting equipment - what tools do you need?

In the powder coating procedure, the application of a coloring agent is not the final stage. In order for the composition to reliably adhere to the surface, the product will need to be heated in a special oven.

To apply the paint, you will need a sealed chamber in which the work will be performed. Spraying will require an electrostatic spray gun. Due to the presence of static electricity, the paint will be evenly distributed over any design.

For the procedure, you will also need a compressor, which should be connected to the painting chamber. On the large productions the number of necessary also includes devices for moving painted objects. This is necessary in cases of painting large and heavy structures.

Color application procedure

Painting of products is carried out in a specially prepared chamber, to which a compressor is connected to pump out air. Dimensional objects are painted in walk-through rooms, and small ones - in dead-end chambers. In more technological production, the paint is applied with special guns controlled by people from outside.

The entire spraying procedure is carried out with a gun. In it, paint particles are charged, after which they are sprayed onto the surface of the product and stick. The algorithm of work is as follows:

1. In a special hopper, the paint is mixed with air. Valves are used to adjust the proportion;
2. The mixture passes through an atomizer equipped with a high voltage source;
3. As a result, positively charged particles are sprayed over the product and quickly set to its surface.

During the operation of the air pumping system, particles that have not had time to charge are sucked out of the chamber. Outside, they fall into a special bunker so that they can be used again or disposed of.

How does the polymerization process take place?

After applying the paint, the product must be placed in an oven, where the part will heat up under conditions of high temperature, and the paint on it will begin to harden. The particles of the composition will melt, resulting in the formation of a film. Immediately after this, the product should cool down. The polymerization procedure will take no more than 20-35 minutes.

Temperature is very important factor for the successful drying of the paint. It should reach 170–200 °C. With its help, the molten particles will fill all the microcracks, forming a perfectly even and durable film.

The coloring composition will begin to acquire all its properties in the process of hardening. It will take at least 20 minutes for the product to cool completely. In this case, the structure should cool naturally, but the use of any devices for cooling is strictly prohibited.

Powder coating is modern technology, which allows you to achieve a reliable and durable coating on almost any surface. Application does not represent special work with skills, but requires the use of special equipment. A feature of this method is that the painting takes place in a dry way, and protective layer formed on subsequent heating.

Although the powder staining method has been known for quite a long time, its technical development began relatively recently. During this time, several ways of carrying out the process have appeared.

The demand for the first method of painting is explained by the fact that this option has a greater technological development. With other methods, everything is more complicated: the second method needs careful selection of temperature, and the third one appeared relatively recently.

Necessary equipment

Although the number necessary tools and fixtures depends on the scope of work, the following is required:

Naturally, large industries have special systems suspensions and delivery, which facilitates the work and speeds up the pace.

Whatever method of applying the composition is used at the finishing stage, the part must be heated in the oven

On a note! Heating, which is necessary in the last stage of dyeing, does not allow the process to be carried out with materials subject to thermal deformation. Therefore, the most popular is the processing of metal parts and elements.

Advantages and disadvantages

Powder coating has many positive properties, among which stand out:

But with all the advantages, the method is not without its drawbacks:

On a note! Usage powder method really very rational, but in terms of design it is inferior to other options. Although at present there are special mixtures with different visual and tactile effects.

It is impossible to achieve high-quality results without high-quality equipment.

Work order

The technology of powder coating of various metal products is a set of measures. A detailed list of works includes an important stage - the preparation of the subject, the quality of which determines the result.

Training

You need to do the following:

The surface is thoroughly cleaned. For this, a number of procedures are carried out:

A conversion sublayer is formed. It is necessary to protect the surface from the ingress of various contaminants. The compositions for this are selected based on the type of material being processed. So, for aluminum parts, chromic anhydride is used, and for steel, iron phosphate is used.

If required, passivation is performed. This process is aimed at fixing the anti-corrosion coating.

Should know! The stages of preparation may vary depending on which products are processed and their scope of application. Sometimes a thorough cleaning and degreasing is enough.

Dye application

Powder coating of metal is carried out as follows:

Painting is considered complete. After 30 minutes, the metal product is removed from the furnace and cooled, after complete cooling the element is ready for use.