Thermography of the polymerization furnace: why it is important and how it works

Often, the production does not even think about how little things can affect the quality of the coating, and generally forget about the safety of workers. Workers forget that they are actually working with machines that sometimes fail, regardless of the manufacturer. They often forget that each product, including equipment, is in constant operation, has its own clear terms and conditions of work. If you do not observe them and torture equipment more than necessary, you can create dangerous working conditions for yourself.

Therefore, for each stage of applying powder paint, for each element of this large system, there is a list of tasks that they must perform, and there are also duties of employees of enterprises to control and regulate their work. After all, no matter how automated the powder coating line is, there must still be someone who turns it on and off. In this case, it is also the one who will monitor the proper work, all the processes, someone to perform manual work, where the system cannot cope, as well as necessarily those who will regularly check the effectiveness of the work and will be able to point out pernicious causes and remedies.

The role of the polymerization furnace in terms of poor adhesion

One of the important factors in the production of powder coat that must be monitored is the polymerization furnace operability. Namely, we are talking about the implementation of thermography and its importance for creating a high-quality coating.

According to the rules, the thermography of the polymerization oven must be performed at least once every 6 months. It would seem that the verification process does not require complex movements, but for some reason everyone often neglects it, until they get bumps from their own experience and understand their mistakes. Although it will be too late, the material is spoiled, the customers are unhappy, and the reputation has long been below the baseboard. To prevent this from happening, we recommend you to pay attention to thermography, not as a desirable, but to a mandatory process.

Thermography as a solution or prevention?

Thermography of a polymer oven is a test of the correct distribution of the temperature rise and the rate at which the required indicators are achieved. Clients often come across problems with poor quality coating and poor adhesion. Of course, the first thing that pays attention to is the quality of passivation and surface preparation for painting, the grounding of products, the quality of the powder supply. But what if the temperature conditions in the polymerization oven do not meet the standards at all? It would seem that the temperature roughly ranges from 170-200 degrees. But it is precisely these fluctuations that can lead to unsatisfactory temperature conditions, in which the paint will not harden in places.

In order to avoid such undesirable consequences, a regular examination of air flows and temperature in the furnace is necessary, which is performed as follows:

• clear temperature measurements are made and recorded during all stages of heating the air in the furnace, as well as in different areas (four measurements are enough, more details on which ones …);
• the difference in fluctuations is investigated and acceptable limits are installed;
• determines how satisfactory certain temperature conditions can be for different types of paint.

Where to start?

Measurement №1 

The temperature is measured when the product is loaded into the oven at its entry point. The temperature should rise in 10 minutes to 200°C and remain stable. Deviations are possible, since some ovens can heat up to 190 degrees, but in no case should the temperature difference in one plane fluctuate by more than 15 degrees during those 10 minutes of stay. That is, for example, the temperature at the entrance to the chamber is 172°C, and after a few minutes it became 189°C. This will be an unsatisfactory indicator, since the difference exceeds 15°C. Thus, it turns out that the total temperature does not even reach 180°C, not to mention the required 200°C.

Measurement №2

The temperature is measured to the right of the entrance to the furnace above products, the thickness of which is about 1 mm in the same stable mode 200°C / 10 min. It is worth saying that this indicator is not ideal, but only a standard, although for some types of paint the oven is heated only up to 180°C and this is quite enough. The temperature is also measured during the entire polymerization time and whether the fluctuation reaches more than 15°C can be traced.

Measurement №3

According to the same principles, it is necessary to investigate the difference in temperature indicators on one suspension. A small hint regarding the ideal temperature for a particular oven – usually a manufacturer of high-quality paint will accurately indicate the indicators and all the nuances of setting up the equipment. Therefore, not reading the instructions in this case is a fatal mistake. Indeed, if the required temperature for melting the paint is indicated at 200°C, and the oven malfunctions and does not reach 175°C due to its fluctuations, then the probability that the paint will adhere to the surface will be ultra low. Poor adhesion is a source of terrible defects. 

Measurement №4

By analogy, we measure the left of the placed products, along the left wall of the furnace. Thus, we will be able to trace which sensors the temperature was more or less stable, which means where the system works well, and where there may be a failure.

Troubleshooting

If you managed to investigate the errors of the polymer oven and clearly determine which area distorts the coating, the steps will be as follows:

• Firstly, in the settings of the curing oven there is often a function for setting the permissible error. It should not exceed 15 ° C. Check if your oven has its own plans for temperature fluctuations, and will correct the value.
• Secondly, it is necessary to modify the raised floor, thus the temperature will be distributed faster and better over the entire surface, but there will be no sharp differences either between areas or between the total value during the polymerization time.

With regular examinations, you can monitor the causes of poor adhesion and help create a better, more reliable coating.