How to get an even supply of paint with poor fluidization


One of the most common problems that can occur during the painting process is the uneven supply of paint from the paint gun. Then the paint settles in inflows, and accordingly the paint film during polymerization does not have the opportunity to spread evenly. If there are layers of paint, in addition to the visible defect, there is a chance that the paint will start to chip, and holes will form. A worker holding a spray gun and directing paint is unlikely to affect how evenly it is sprayed. The reason lies much deeper here, namely in the system of paint supply and its charge. 

Powder coating is a process that does not require high labor costs. Usually powder coating lines are maximally automated, but even with minimal human exposure, defects often occur. Most of them are due to incorrectly selected paint and equipment settings, some due to non-compliance with all application rules, and there are those that occur due to insufficient control over the condition of the equipment. Unfortunately, even the highest quality equipment has its expiration date. Therefore, it is extremely important to monitor its condition and performance. Any errors, fatigue of the metal from which the device element is made, can lead to a spoiled batch of products.

In general, the speed and quality of powder supply is affected by nothing but air, namely its correct supply. Air plays a significant role in the application of paint, because it helps to loosen the paint in the container while it is preparing for use. This is called the fluidization process. Then the paint rises under air pressure and also under air pressure extends to the product. In some equipment, air is also used to clean and purge the equipment. All processes affect the quality of powder supply. If such a problem occurs, it is necessary to check from the very first factor in the sequence of application. First of all – check up serviceability of processes at fluidization!

Fluidization of powder paint

Fluidization of powder paint – a stage in which the paint powder is loosened in a special container before serving. This is usually a special tank, at the bottom of which is a special plate with holes through which air is supplied. It tosses the powder particles, thereby loosening them, mixing the recovered paint, which is returned to the tank, with fresh. Fluidization is not an additional option at all, but a mandatory process and we will explain why.

The powder stays in the paint supply tank for a while. Because these particles are made of resinous substances, it has the ability to depend, to accumulate in lumps. Therefore, it is very important to keep him in motion. Then each particle will be separated from the other, which allows you to control the uniform transportation and supply.

If you suddenly notice problems with paint layering, gaps, sharp feed waves, etc., note the following errors in the fluidization process:

  1. Not enough air to loosen

As already mentioned, the air is fed through a mesh or plate with holes in such a way as to throw particles of powder and gradually mix. The air must be supplied with such pressure that all the particles move. If the pressure is insufficient, the bottom layer will mix, but the top layer will remain stationary. In general, the fluidization process should resemble boiling water. Then all the paint will be mixed and will be easily applied to other processes. Stirring also plays an important role in recovery. Each paint spray chamber is equipped with this system. It consists in the fact that through special holes in the chamber the remnants of paint are absorbed, which was not electrified on the product, but just flew in the chamber. This paint is collected, the charge is removed from it, then it is filtered from possible contamination and finally it gets back into the paint tank. Now it is ready for use again. But it is still very important to remember: the amount of recovered powder should not exceed 20%. If we do not follow the thorough mixing, only the recovered paint can be sprayed on certain areas, and it already has a slightly weaker ability to charge. As a result, not only layers of paint, but also unpainted areas.

  1. Grid clogging in the air supply partition

So, in the tank with paint instead of the bottom of the special plate studded with holes. Air is supplied through it in small streams. And what can prevent his filing? Clogging holes. Unfortunately, there are many factors in industrial production that can cause this: from the humidity due to which clogging occurs by wet paint particles, to the ingress of industrial dirt, dust and oils. If there is no necessary air supply, the fluidization process will not be possible. If this happens, the paint will clot.

  1. Wet powder collected in lumps

It is very important to monitor the conditions in which the powder is stored and transported. This is especially true of cardboard boxes. At excessive humidity even at vacuum packing the result will be worse than desirable. Of course, we cannot provide absolute insulation of the paint during transportation. But it is the worker’s conscience that checks the powder. Often it can be traced even by touch. When squeezed in the palm of your hand, the wet powder will collect in lumps and will look like porridge rather than a crumbly substance. If it is really noticeable that the paint is slightly wet – no problem. The main thing is not to operate it immediately, but to dry it. This, by the way, can help the fluidizer. You just need to keep the paint longer and it will eventually dry under the influence of air. It will be an additional 15-20 minutes, but as a result – no defects and quality coverage. Choose for you!

  1. Recuperator share

The recovered powder is returned for reuse almost immediately after collection. On the one hand, it is a great advantage and economy. But do not ignore the rule of 80/20, this is where 20% recuperate, and everything else – fresh paint. Recovered powder may lose some of its properties, so it must be combined with a new paint to compensate for all the shortcomings.

How to fix paint defects and fluidizer malfunctions

Therefore, in order to prevent the paint from sticking, its uneven supply, etc., you need to pay attention to the above factors and take the following measures:

  • adjust the air pressure supplied to the recuperation system;
  • carefully check the clogging of the mesh partition, if necessary, replace them with new ones;
  • check the humidity in the room and systems responsible for its elimination;
  • control the cleanliness of the workplace so that in no case get on the fluidizer, or in any other element of the system, industrial oils, dirt and dust;
  • when starting work, it is necessary to clean the whole system of paint every time, then load fresh, regularly check the proportion of recuperant and fresh paint;
  • monitor the level of powder in the tank: it should not exceed ⅔ total volume, so that there is enough space for efficient mixing.

Follow the rules, check everything carefully and enjoy quality coverage.

Плохая флюидизация краски

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