Dyeing process technology. Own business: powder coating. Powder painting equipment and painting technology Cold powder painting technology

Existing technologies painting allows you to simplify the task and speed up the painting of metal products. Thus, powder painting (which partially replaced standard technology) makes it possible not only to qualitatively paint a metal surface, but also to protect it from the influence negative factors. The use of this method also has a positive effect on the appearance of the painted products.

Powder coating application area

The method in question is one of the most widespread and is used in various fields. This technology finds its application in production construction work, in mechanical and instrument engineering. Powder coating of metal is actively used in the automotive industry and in car repairs: the ability of the paint to improve the performance characteristics of the surface, as well as safety and environmental friendliness, makes it the best option for restoration of coatings.

The properties allow the composition to be used for such operations as painting discs with powder paint and a number of others. Choosing this option if you need to restore paint coating car, there is no doubt that it is capable of returning vehicle attractive appearance, reliably protect it from corrosion and exposure unfavorable factors external environment. This effective method copes well with the task of painting both small parts and large elements, including the car body.

Painting work can be done using powder paint yourself, especially if it is a very small part. But such painting requires skills and abilities, so if you need an excellent appearance of the painted element, it is recommended to turn to professionals. If powder coating of metal products is required large area(for example, a car body), without special equipment not enough.

Advantages of powder paint

Compared with traditional ways painting, powder paint has a number of undoubted advantages, including strength and resistance to corrosion, high speed performance, durability, low material consumption, absence of solvents and safety for human health. Painting promotes the formation of protective film which prevents scratches and other damage.

It is also significant that there is no need to create special conditions for storing the composition.

Types of powder paints

Powder paint is divided into two types - thermoplastic and thermosetting. The first option, in turn, is divided into varieties depending on the underlying composition of the substance. Paint based on polyvinyl butyral is recommended for use for painting works indoors, and compositions based on polyvinyl chloride are among the universal ones (for outdoor and interior work). The same can be said about polyamide compounds, which are resistant to various external influences.

There are also polypropylene powder paints, but this option is more aimed at protecting the surface rather than creating decorative covering. Thermosetting coatings can be based on acrylates, epoxy resin and other components. This variety has wide scope applications and can be used, including for painting cars.

What is powder paint?

Powder paint is a fine powder with a polymer structure. The composition of such paints may include various components (hardeners, resins), as well as substances intended to impart color to the composition. The composition of the coating in combination with painting technology can reliably protect metal products from the influence of aggressive environments and give it excellent aesthetic characteristics.

Advantages, benefits, disadvantages

Along with the listed advantages (strength, durability, environmental safety, etc.), you need to pay attention to the fact that this type of paint provides big choice colors and shades, so it is always possible to choose suitable option. As for the benefits, such painting is one of the economical options: almost 100% of the material is used, leaving no large quantity waste.

The disadvantages of paint include the need for constant monitoring of the painting process in the chamber and the difficulty of carrying out work when low temperatures. Additional inconvenience can be created by the fact that each color must be stored in an individual container. But in any case, powder paint is an option that has a minimum of disadvantages.

Powder paint application

To work with powder paint, it is necessary to set up a paint shop (this will require a space of 100-150 square meters). Important point: such a workshop should not be located near (at a distance of less than 5 m) possible sources of ignition. Powder painting requires careful adherence to technology: only in this case is the expected result guaranteed.

What equipment is required for powder coating technology?

Painting work requires special equipment. In order to paint any product, you will need a paint booth and a polymerization oven, a compressor and a sprayer. Equipment for powder painting includes a complex designed to prepare the surface for painting and some other components.

What should you pay attention to when choosing powder coating equipment?

Purchasing special equipment requires financial costs, so when choosing it, you need to take into account a number of important factors, among which the purpose of its purchase is of decisive importance. Thus, the painting booths on the market can be intended both for single products and for organizing large-scale painting works.

The atomizer (depending on the camera) is contained in the camera or purchased additionally. For household use It is recommended to choose hand guns. Expensive atomizer options cover large area surfaces, due to which painting time is significantly reduced.

Preparing for painting

The quality and durability of the coating are largely determined by the preparation for painting. Preparatory measures include thorough cleaning and degreasing of the surface, protective treatment and phosphating (required to improve adhesion). The process is often completed by passivation, which involves treating the surface with chromium nitrates and sodium (increases corrosion resistance).

Technological process

Immediately before painting, the product to be painted must be masked, i.e., those elements that do not need painting must be reliably protected. Masking is also required when painting with several colors. After preparatory activities and masking, begin the process of applying paint.

Applying paint

The coating is evenly applied to the surface using a sprayer. It is recommended to ground the product that is being painted: this helps to retain particles on the surface. Then the painted product must be placed in an oven (the layer should melt and a film will form on the coating) and cooled in the fresh air.

Coating quality control

After removing the product from the oven and cooling, the coating becomes hard. However, it is too early to transport or use it: to complete the process, you need to wait 24 hours (during this time the coating will gain maximum strength).

Thus, the type of painting in question is an effective method of painting various types products. The use of this technology allows not only to give the product an excellent appearance, but also to reliably protect it from the influence of aggressive environments.

Powder coating of metal was invented back in the 60s of the last century and very quickly became widespread. This is due to the many advantages of this technology, such as efficiency, environmental friendliness, and attractive appearance of the coating.

General information

So, the meaning of this technology is that a polymer powder dye is sprayed onto the surface to be painted. That is why this method and got this name. After applying the dye, the surface is exposed heat treatment, as a result of which the powder melts and forms a continuous uniform film.

The coating obtained by this method has the following properties:

• Corrosion protection;
• Good adhesion to the base;
• Resistant to temperature changes;
• Resistant to mechanical damage, including impact resistance;
• Moisture resistance;
• Resistant to chemical influences;
• Excellent decorative properties;
• Durability.

Advice!
Due to good adhesion, this method is the most optimal option for painting stainless steel.

Separately, it should be said about the decorative properties of such a coating, which is distinguished by a variety of colors and textures, which is achieved through the use of various additives.

In particular, powder coating of metal allows you to obtain following types surfaces:

• Matte;
• Glossy;
• Flat or voluminous;
• Imitating gold;
• Imitating wood texture;
• Marbled;
• For silver, etc.

Advantages of powder painting technology

In addition to the possibility of obtaining a coating with high performance qualities, this technology has a number of other advantages, such as:

• Possibility of application coloring composition one layer, which is unacceptable when painting with liquid paints and varnishes.
• No need to use solvent and control the viscosity of the material.
• High dye efficiency, since the powder that has not settled on the surface to be painted can be reused. To do this, spraying is performed in a special chamber, which allows you to collect all unspent powder. As a result, the cost of powder painting of metal is lower than applying paintwork using other methods.
• The painting process takes a little time, and after applying the paint, you don’t have to wait for it to dry.
• Environmental Safety, since the dye does not contain toxic organic compounds. As a result, there is no need to use powerful ventilation systems.
• Highly automated dye application technology, which simplifies the process of learning how to operate the equipment.

Flaws

Like any other technology, powder coating metal has some disadvantages:

• It is impossible to eliminate local coating defects - if they occur, it is necessary to completely repaint the surface.
• It is impossible to do the painting yourself, as this requires special equipment and workshop conditions.
• The dimensions of painted surfaces are limited.
• – it is allowed to use only powder paints for metal from manufacturers.
• It is impossible to paint parts that will later be welded, since burnt areas of the coating cannot be restored.

Powder painting technology

Preparing the base

Pre-treatment is the most time-consuming and labor-intensive stage of painting. However, it needs to be given Special attention, since the elasticity, durability and quality of the coating depend on preparation.

Preparing a part for painting involves removing any contaminants, degreasing the surface, and phosphating to improve adhesion and protect the metal from corrosion. The surface to be treated is cleaned mechanically or chemically.

To remove oxides, rust and scale, effective method cleaning is shot blasting. They are realized using sand, steel or cast iron granules.

Under influence compressed air or centrifugal force, these particles are fed at high speed onto the surface being treated and crush it. As a result, scale, rust and other types of contamination break off from the metal, which significantly improves adhesion.

The chemical cleaning method is called etching.

In this case, the removal of rust, oxides and other contaminants is carried out using compounds based on the following types acids:

• Solyanoy;
• Nitrogen;
• Sulfur;
• Phosphoric.

The advantage of etching over abrasive cleaning is greater productivity and ease of use. However, after this procedure it is necessary to rinse the surface thoroughly. Accordingly, costs arise for the use of additional cleaning products.

In the photo - painting a small part

Applying paint

After completing the pre-treatment of the metal, the part is placed in a special chamber where coloring powder is sprayed. As mentioned above, the camera is needed to catch unused material. In addition, it prevents paint particles from entering the room.

Such chambers are equipped with cleaning means such as hoppers and vibrating screens, as well as suction systems.

It must be said that there are two types of cameras:

• Walkthroughs - for painting large-sized products;
• Dead-end – for painting small objects.

In addition, there are automatic models in which the coating is applied using automatic manipulator guns. Of course, the price of such equipment is the highest, however, its performance is also much higher - powder coating in this case it is applied literally in a matter of seconds.

As a rule, paint is applied electrostatically, i.e. Electrostatically charged powder is sprayed, which envelops the grounded part and adheres to it. The spraying itself occurs using a pneumatic sprayer, which is either simply a pistol.

After spraying the powder, the product is moved into the oven chamber, where it is subjected to heat treatment. Under the influence of high temperature, the powder transforms into a viscous-fluid state, after which the melted particles form a monolithic layer.

Note!
To obtain a high-quality coating result, the operating instructions for the equipment must be strictly followed.
Therefore, this work should be carried out by a specialist.

Conclusion

Powder painting of metal surfaces is in many ways more advanced than painting with liquid paints. However, in some cases its use is limited. In addition, it can only be performed using expensive professional equipment, so it is not applicable at home.

For more information on this topic, watch the video in this article.

Powder painting is modern technology, which allows you to achieve reliable and durable coating on almost any surface. Application is not particularly difficult if you have the skills, but requires the use of special equipment. The peculiarity of this method is that painting occurs in a dry way, and protective layer formed upon subsequent heating.

Although the powder coating method has been known for quite some time, its technical development began relatively recently. During this time, several ways to carry out the process have emerged.

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

Necessary equipment

Although the quantity necessary tools and equipment depends on the scale of the work, the following must be present:

Naturally, large productions have special systems suspensions and delivery, which makes work easier and speeds up the pace.

On a note! Heating, which is necessary at 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 the most notable are:

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

On a note! Using the powder method is indeed very rational, but in design terms it is inferior to other options. Although currently there are special mixtures with different visual and tactile effects.

Work order

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

Preparation

You need to do the following:

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

A conversion sublayer is formed. It is necessary to protect the surface from various pollutants. Compositions for this are selected based on the type of material being processed. Thus, chromium anhydride is used for aluminum parts, and iron phosphate is used for steel.

If required, passivation is performed. This process aims to consolidate the anti-corrosion coating.

You should know! The stages of preparation may vary depending on the products being processed and the scope of their application. Sometimes it is enough to carry out thorough cleaning and degreasing.

Applying dye

Powder coating of metal is carried out as follows.

Powder paints were developed in the 60s of the 20th century due to the need to protect painted surfaces and give them an attractive appearance. appearance, reducing painting costs, as well as in order to reduce harm to the environment. At the same time, the electrostatic coating method and the anodizing system emerged. Coatings with a metallic effect and paints that are resistant to adverse external factors began to appear.

The polymer powder coating is first sprayed onto the product, and then polymerized in a special oven at a certain temperature. Powder painting technology involves the following steps:

• Surface preparation
• Powder paint application
• Polymerization

Surface pre-treatment

Pre-treatment of a product is the longest and most labor-intensive process, which is sometimes not given the necessary attention, while the durability, quality and elasticity of the coating depend on it. Preparing the surface for the painting process includes removing any contaminants, degreasing and phosphating in order to increase adhesion, as well as protect the metal from corrosion.

Cleaning of the treated surface can be carried out mechanically or by chemical means. In case of mechanical cleaning, steel brushes are used or grinding discs, rubbing in with a clean cloth soaked in solvent is possible. As for chemical processing, it is carried out using acidic, alkaline or neutral substances and solvents, which are selected depending on the degree of contamination, material, size and type of surface being treated and other factors.

Application of a conversion sublayer prevents penetration under the coating various kinds dirt and moisture that cause peeling and subsequent destruction of the coating. Phosphating the surface with the application of a layer of inorganic paint makes it possible to increase adhesion, that is, the adhesion of the surface to the paint by 2-3 times, and protect it from rust. When removing oxides (scale, rust and oxide films), abrasive (mechanical, shot blasting, shot blasting) and chemical cleaning, that is, etching, are very effective.

• Abrasive cleaning is carried out using small particles (shot, sand), cast iron or steel granules, nut shells, which are fed to the surface at high speed using compressed air or centrifugal force. These particles break off pieces of metal with scale, rust or other contaminants, which significantly increases the adhesion of the coating.
• Pickling is the removal of oxides, rust and other contaminants using solutions based on hydrochloric, sulfuric, nitric, phosphoric acids or caustic soda. They contain inhibitors that slow down the dissolution of the cleaned surface. Advantages chemical cleaning before abrasive – this is greater productivity and ease of use. But after it, you need to rinse the cleaned surface from solutions, and this, in turn, makes it necessary additional use cleaning agents.
• The final stage of surface preparation is passivation. In other words, the treatment of the body with compounds of sodium nitrate and chromium. Passivation is carried out in order to prevent the appearance of secondary corrosion at any stage of surface preparation - after degreasing, phosphating or chromating.

Once the part has been rinsed and dried in the oven (curing section), the surface can be considered ready for powder coating.

Applying powder paint to the surface of the product

When Preliminary processing finished, the object to be painted is placed in the spray chamber, where powder paint is directly applied to it.

The main purpose of this box is to catch powder particles that have not settled on the product being painted, dispose of paint, and prevent it from entering the room. Such a chamber is equipped with a filter system, cleaning means (vibrating sieve, bins, etc.) and suction systems.

There are dead-end and walk-through types of boxes. Products are usually painted in dead-end chambers small size, while large items are classified as long items. There are also automatic models, where powder coating is applied in a matter of seconds using manipulator guns.

The most common method of applying powder paint is electrostatic spraying, that is, applying an electrostatically charged powder to a grounded product using a pneumatic sprayer, also called a gun, applicator or spray gun.

Formation of coating

When the paint has already been applied to the product, it is sent to next stage– coating formation, which includes melting the paint layer, obtaining a coating film, its hardening and cooling.

The reflow process is carried out in a special oven or chamber. There are many types of polymerization chambers; depending on the specifics of production, their design may vary. Speaking in simple language, such a stove is a kind of drying cabinet, having electronic “filling”. Using the control unit it is possible to control temperature regime cameras and staining time, configure automatic shutdown at the end of the process. The energy source for the polymerization furnace can be electricity, natural gas or even fuel oil.

There are horizontal and vertical, continuous and dead-end, single and multi-pass furnaces. Melting and polymerization occur at a temperature of 150-220°C for 15-30 minutes, as a result of which a film is formed, that is, the powder paint polymerizes.

The main requirement for polymerization chambers is to constantly maintain a set temperature for uniform heating of the product being painted. The required mode for forming the coating is selected taking into account the characteristics of the product, the type of powder paint, the type of oven, etc.

At the end of polymerization, the part to be painted is cooled in air, and after it has cooled, the coating can be considered ready.

When processing large parts or large production volumes, a transport system is used. Thanks to it, painted products can be easily moved from one painting stage to another. The principle of operation is that the objects to be painted are supplied on a special suspension or trolleys moving on rails. Such a transport system makes it possible to continuously carry out the painting process, which, in turn, can significantly increase work productivity.

Benefits of Powder Coatings

Metal powder painting technology has many advantages:

• Excellent physico-chemical and decorative properties coatings that cannot be achieved by other painting methods, including a rich palette of possible color solutions.
• Good operational properties coatings
• Durability of products painted with powder paints
• One-layer coating thanks to 100% dry matter content, which means the use of powder paints is economical
• Low porosity
• Improved impact resistance and anti-corrosion properties compared to other paints
• There is no need to control viscosity, since powder paints are supplied directly to the consumer in ready-to-use form
• Losses when painting with powder paints are 1-4%, and, for example, when using liquid paints– about 40%
• Coating hardens within 30 minutes
• No need for large powder paint storage areas
• Minimum damage to painted parts during transportation and reduced packaging costs
• Environmental safety of powder coating

In view of all the above advantages this method metal coloring, most industrialists today give their preference to it.

Powder coating of metal – modern method painting and protecting surfaces. Liquid coating with powder particles is applied to the part to be painted. Particles are held on the surface by electrostatic attraction. At high temperature fine powder particles melt and polymerize, forming a single high-quality coating.

Characteristics and scope of application of powder coating

Powder paint - liquid composition on the base polymer resins with hardeners and flow modifiers. Pigments are added for color. The processing temperature in the chamber is 200–250 degrees. Powder coating technology is used for products that can withstand the temperature at which the coating bakes without deformation.

The most widely used technology is:

• V industrial production metal products;
• in the production of building materials.

Glass, ceramics, MDF are also painted using this method.

Powder coating covers a wide range of goods and structures, including:

• furniture, household appliances;
• medical instruments, equipment;
• Sports Equipment;
• sheet metal, aluminum profiles.

The main advantages and disadvantages of powder coating

Powder painting protects the surface well. The paint is applied in a dense layer, 35–250 microns thick, with fewer pores. One layer replaces 2–3 layers regular paint. The smooth, durable film of the coating does not scratch and is not damaged during transportation.

The production technology allows you to collect paint sprayed in the air for reuse. Losses of the coloring composition are minimized, amounting to 1–4% of the total mass. The process of painting metal is simple, not labor-intensive, and does not require a large number of workers. These factors reduce the cost of application on square meter designs.

Corrosion of metal painted in this way is excluded. Metal products do not fade under sunlight, color, quality of coating does not change in any weather conditions. The varied palette has many shades and reproduces the complex textures of bronze, granite, and silver. The gloss varies from matte to gloss.

Powder paint is supplied by the manufacturer ready for use; no solvent is used. Parts for powder coating are not primed.

The disadvantages of powder coating include:

• the composition is not tinted, the choice comes from a ready-made palette of shades;
• impossibility of applying manually, only in workshop conditions using special equipment;
• If there is a defect in metal painting, it is impossible to correct a separate section; the entire part must be repainted;
• the material of the metal part must withstand 200–250 degrees, which is not always possible;
• The dimensions of the parts depend on the dimensions of the polymerization chamber.

Type of powder coating

Metal painting takes place in three stages. Powder paint is applied to the prepared surface. After spraying the paint composition, the part is sent to an oven for polymerization.

The following equipment is required for painting:

• Application chamber. Equipped with air suction to collect paint, return it or dispose of it.
• Pneumatic spray gun. Together with the feeder it forms a tool for applying powder coating.
• Feeder.
• Polymerization chamber. Creates sufficient temperature to complete the process.

The installation, consisting of a spray gun and a feeder, creates a mixture coloring matter with air, forms a torch, gives electric charge paint particles. The shape of the torch depends on the installed gun nozzle. Charged particles, settling on the workpiece being processed, are held by the force of electrical attraction.

Existing overlay methods

Methods of application based on the type of charge received by particles are called electrostatic and tribostatic.

Using the electrostatic method, the charge is imparted by a corona electrode under a high voltage of 20–100 thousand V. Electrostatic units are more powerful and productive. As the electrode voltage decreases, the speed of the air stream increases.

The tribostatic effect is achieved by the friction of particles against each other and the material of the gun body. The body of the gun is made of fluoroplastic to increase friction.

Tribostatic installations are cheaper, the performance of the units is lower than that of electrostatic ones. The percentage of particles deposited on the part is lower. Not all metal paints are designed for friction charging; you need to choose special ones or use adapting additives. Gun parts wear out and require replacement. It is more convenient to process parts using the tribostatic method complex shape, grooves, recesses. The electrostatic method is not effective under such conditions and leaves unpainted marks.

Based on the resin composition, mixtures are divided into three categories:

• epoxy paints;
• epoxy-polyester compounds;
• polyester paints.

Epoxy Powder Coatings

Epoxy paints for metal are durable and resistant to chemicals, oil, fuel. They do not require a primer; they themselves can be used as a primer layer before applying liquid powder coatings. The thickness of the applied layer is up to 500 microns.

Epoxy paint does not conduct electricity; for its insulating properties it is in demand in the electrical and radio engineering industries when painting metal, which requires increased anti-corrosion properties. Ferrous metals, galvanized steel are phosphated, aluminum and aluminum alloys are chromated. An impact-resistant coating with good adhesion is formed.

Epoxy-polyester coatings are more decorative. Based on them, it is possible to obtain complex textures like embossed leather, aged surface effects, and a wide palette of metallic shades with varying degrees of gloss. The disadvantage of epoxy-polyester coating is reduced paint resistance to atmospheric phenomena and poor resistance to metal corrosion processes.

Polyester powder paints are weather-resistant, mechanically strong, abrasion-resistant coatings. High adhesion polyester compositions allow coating on all types of metals, including light alloys. They insulate electricity well. By reacting with alkali, the paint layer is destroyed.

Features of powder coating technology and polymerization

The application of powder paint takes place in three stages:

1. Surface preparation. Includes removal of contaminants and application of additional conversion coatings to enhance protective properties and durability.
2. Painting in paint booth using the installation.
3. Polymerization in an oven at high temperature.

Chemical degreasing of metal before painting is mandatory. Residues of oil, chemicals or drops of moisture can cause stains with discoloration, punctures, and pitting. The workpiece is inspected for the presence of sharp edges, burrs, burrs from welds And .

It is necessary to clean the surface from rust and dust. Giving additional properties surface phosphating, chromating or passivation depends on the coating requirements.

The application chamber is equipped with a recovery system that returns microparticles to the feeder.

The curing temperature of each type of paint is indicated by the manufacturer in the accompanying documents and, as a rule, is 180–200 degrees. The polymerization temperature refers to the surface temperature of the workpiece, and not the operating temperature of the furnace.

It is recommended to cure the paint in a polymerization chamber at low temperatures and for long periods. This will increase hardness and avoid coating defects such as shagreen and drips.

It is recommended that massive metal products be heated in advance so that the time the part remains in the oven is sufficient for final hardening. Dust is not allowed in the room. It is prohibited to transport a metal product with uncooled paint.