Powder painting of metal doors

Powder painting of doors is a technological process, as a result of which microscopic particles of dry paint material, which has a positive electric charge occurs. The charge is formed by friction or from a source from the external environment. The processed part has a negative charge, so that the powder settles on it. Next, the surface is heated, the powder applied is melted and a reliable coating in the form of a film is created. This method of applying coloring material is suitable for processing surfaces made of metal.

Table of contents:

1. Advantages of powder coating
2. Disadvantages of powder coating
3. Selection of equipment for work
4. Preparation of the surface for painting
5. Powder coating technology
6. Baking the applied powder coating

Advantages of powder coating

Comparing the coloring with a classic coating with liquid paint, a lot of advantages of powder staining are detected:

• Environmental purity. The powder is made without the use of toxic and fire hazardous substances.
• Economy. The consumption of the powder occurs moderately, and not the particles settled on the surface remain for the next staining.

• A high resistance to chemical and physical influences.
• Uniform distribution of the coating on the surface.

• The absence of the need to apply a primer.
• The ideal coating is formed when surface processing with only one layer of paint.
• The total percentage of the loss of raw materials when treating liquid paint is 40%, when surface treatment with powder, this indicator is 4%.
• The total working time with the powder is much less, since it is completely fixed after 1.5-2 hours.
• Storage of powder for painting is carried out without creating specific conditions.
• The products painted with powder are also not demanding on operating and transportation conditions.
• It is not at all difficult to paint the surface with the powder, this does not require special skills.
• During staining with powder, poisoning with toxic secretions is excluded, since they simply do not.

Disadvantages of powder coating

With all the wealth of the list of advantages, painting doors with powder paint has its drawbacks.

• The technology of staining requires the creation of the melting temperature of the powder at a level of 150-220 degrees, which excludes the ability to process the surface of plastic and wood in this way.

• The powder coating has a higher cost than ordinary liquid paint.
• Equipment for painting has a narrow circle. A small furnace will not process the coating of a large area. A large furnace is ineffective when working with small details.
• Difficulties in applying a thin layer of paint.
• At low temperatures, it is difficult to carry out work with powder.

Selection of equipment for work

Before starting work, equipment is prepared for the entire process. The most important device is a special camera, the main part of the entire staining process is carried out in it. Technical characteristics of the device are selected in accordance with the material and type of part of the processed part.

This camera actually consists of the camera itself, the powder is sprayed in it, and the stove for swimming. If it is planned to paint metal doors with your own hands, then it is not necessary to purchase all these units. An ordinary oven is also suitable for smelting the coating.

In addition to the chamber, a pulverizer with electric power is used in the process. Such models have a function of turning on compressed air. In the absence of such a gun, it is replaced by a compressor, which is equipped with a working filter for high pressure.

The choice of room for powder painting of metal doors is also very important. It should be well illuminated, preferably lamps of daylight. They are suitable because during the performance of the work the powder will not stick to the hot surface of an ordinary lamp. In domestic conditions, the optimal room for such work is the garage. A good ventilation system must be equipped.

Another important element device for collecting powder remains. It helps save material, reducing its consumption to a minimum. A recuperator is well suited for this purpose, but an ordinary vacuum cleaner is also adapted. But during work using a vacuum cleaner, it is necessary to ensure that its filters do not clog, models with a solid filter are optimally suitable. Before starting work, the condition of the electric network is checked, it must withstand heavy loads and have good grounding.

During the painting of large parts, a special -purpose transport system is used. It provides easy movement of parts during the entire process. On an industrial scale, such a system works on the principle of a conveyor that accelerates and optimizes the process. The transport system for coloring is carts or mechanisms moving on rails.

Preparation of the surface for painting

When processing parts with staining powder, they often do not pay attention to the preliminary preparation of the part. But, as in the implementation of any other finishing or repair work, the preparation has a great influence on the quality of the work performed further. The same applies to the processing of such a part as the doors of the input metal. Powder painting is demanding on the purity of the working surface. It is necessary to remove all the spots available on it, degrease the door and phosphate. This measure is not necessary, but will help increase the resistance of the metal to corrosion and improve adhesion.

The material is cleaned with the help of chemicals or by the mechanical method. The mechanical method is a cleaning of the door with a brush of steel or a disk for grinding. The surface cleansing is applicable with a clean piece of cotton material impregnated with a solvent. In chemistry processing, alkaline, acidic or neutral substances are used. What substance is optimal to use depends on the type of pollution, varieties of the cleared material and its total size.

Phosphating is applying a convertible sublayer to the surface. It is necessary to exclude the likelihood of a layer of coating of liquid and solid molecules, which destroy spraying and lead to detachment from the base. Also, this procedure improves the coupling of staining powder with metal.

If there are traces of rust, scale, oxide film, then they are removed by an abrasive or chemical method. The abrasive method is also cleaning the surface using small grains of sand, fraction. Larger particles are applicable, such as granules made of steel, cast iron, walnut shell and similar materials. Particles are submitted to the affected area under the influence of centrifugal force or stream of compressed air. By force, hitting the metal, they knock down and take away its most vulnerable places, that is, areas with pollution, while the uninterrupted material remains untouched.

Cleaning with chemistry or etching removal of affected areas with solutions with such a main component as nitrogen, hydrochloric, sulfur or phosphoric acid. Such solutions contain inhibitors that slow down the destruction of clean areas. The disadvantage of this method in the need to carefully remove the residue of the solution from the material. For this, special washing tools are used, the acquisition of which increases the total cost of work.

The last stage of preparation Passivation. This procedure is a surface treatment with a connection of chromium and sodium nitrate. This process is necessary to prevent corrosion at all stages of processing. After applying the solution, the part is left to dry, after which it is considered ready for applying powder paint.

Powder coating technology

Having completed the preparatory processes, metal doors begin directly. This procedure is professionally carried out in a special chamber, the main function to capture it not settled grains of powder. Such an unit is equipped with a filter system, vibration, bunker and suction system. The very method of covering the powder is electrostatic spraying loaded particles applied to the grounded element. As a tool for applying the powder, a spray gun acts.

Painting of metal doors is independently carried out with some modifications of tools for this process. Performing this work at home, without using the camera, the part is simply suspended on the hook and combined with the minus from the PSU. To create the necessary voltage, you will need a generator and multiplier. The wires for installation choose the corresponding voltage of 25 square meters.

The gun to perform work is combined with a device loading powder. At home, an ordinary plastic bottle is used for this purpose. The air for work should be compressed and dry. A metal cover is put on the selected bottle, the material should be a good current conductor. A lot of small holes are made in the lid, tension will be supplied to it. Further, everything works very simply when pressing the plastic sides of the bottle creates a pressure drop, which pushes the powder through the holes of the lid, passing through which the powder receives the necessary charge.

Such a device has many opportunities for modernization, also the idea described above is used to equip a conventional sprayer for powder painting of metal doors. The video below shows just such a home -made device. To measure the voltage supplied to the lid, it is brought to the parts, if the spark jumps at a distance of 2.5-3 cm, then the voltage corresponds to the necessary parameters. As for the camera, it is replaced by ordinary newspapers, a plastic film, a vacuum cleaner or a recuperator at home.

Baking the applied powder coating

The main stage in the process of applying the staining powder is not in preparatory processes and not in the surface of the surface by the powder itself. The most important and crucial stage in the formation of the coating. During the formation, the coating is melted, hardened and then cooled. All this passes in a special furnace or camera. In industry, various types of these devices are used, which vary depending on their purpose. On a household scale, this unit is replaced by an ordinary dryer cabinet with electronic components.

Cabinets for surface formation during powder staining are equipped with a temperature control system inside the device. They also have the opportunity to configure the automatic shutdown of equipment at the end of the baking. Such equipment is powered by electric shock, fuel oil or gas. The stoves in their design are divided into horizontal, vertical, dead -end one -pass and multi -pass.

The technological process of baking the painted part takes place at a temperature of 150-220 ° C. In time, it takes about 15-30 minutes. As a result of the passage of such processing, a film is formed on the surface, that is, the powder is polymerized. The camera should keep the temperature at the same level, otherwise the product will not warm up evenly and the coloring quality will not satisfy the requirements. The baking mode is selected in accordance with the size of the product, type of paint and a variety of the furnace itself. Cool the product naturally, placing it in the open air. When the temperature of the product decreased to the required level, it is considered completely ready.

At home, for drying with pink with powder paint, the details are adapted by the usual heat cabinet. The temperature in such a device should reach 200 ° C, and the processing time increases to 40-60 minutes. The cabinet is thoroughly insulated from the inside with asbestos or mineral wool. Tenas are used as a heating element in a homemade furnace. To warm up the parts evenly, the furnace is equipped with a convection device.