How to choose a good furnace?

Knowing our position in the field of powder coating, we can say something, the whole truth, that truth is on our side

Furnace for the polymerization of powder paint

1. Distribution of temperatures in the oven.
On the world there are many furnaces, made in different technologies, but to powder coating plants is suitable few of them, which the manufacturer says few about the distribution of temperature in the furnace, and it is the basis! How would you make a choice, not knowing the basic parameters? Many manufacturers in general it does not measure! as so they had to give it to you? Ovens are sorted by classes, but many manufacturers (expensive and cheap) does not even have a clue, no one not forced theirs to know about it, most manufacturers are small businesses employing no more than 20 people.

2. Air flow in the oven
Air-circulation in oven must have channels of distribution air evenly throughout the oven chamber at the same time. If the furnace fan will have to colloquially as "mixed air" and there is no possibility of its dosage in the different sections, there is no possibility that the temperature distribution was identical.

Every self-respecting company that offers a furnaces made in standard AMS used in the aero or automotive, apply regulations the air on the side walls. There are many expensive companies, but are not able to produce furnances in AMS standard.

Well, after what they had to do it, customers had expensive product without such a regulation?

It's simple, if the distance from the heat source is long, and is provided for blowing away the air on the way to cool down, and the temperature difference in the chamber increases. So it's hard maintain a good temperature distribution in the furnace oil with heat exchanger on the side, because the heat exchanger is one and blow needed from eg. 3 meters away. In the case of application our solution this distance is less than half - physics can not be fooled.

3. How resolved to replace the heater or fan?

Professional Furnaces have a modular design. This means that if you burn the heater will not have to disassemble the whole furnace. You pull out the heating module and replacing. The same applies to the fans and their motors. You pull the whole unit, not interfering in the construction of the furnace.
Sure, it's better not to break down, but it will be nice as after 10 years of use, replacement of burnt engine will not be associated with plasma cutting of the ceiling.

4. What are the installed components?

Seemingly obvious, but not. Most customers will look for the names western manufacturers components, and it easiest to just, but we do not belong to those companies who go with the flow.

So what that mounted component comes from a good source, if assumptions are wrong. For example; the standard construction mounted motors have a short standard rollers, are mounted to their couplings, extensions and various additional elements, which are a potential source of failure, cause vibrations etc.
Of course, the manufacturer is significant, the market is full of cheap crap, but the manufacturer of the component should not be a decisive argument here.

For comparison, engines that are mounted in our furnaces are dedicated and combined with the entire fan. This means exactly that have their own engines, which have long cooled roller with a dedicated stocking for the fan, there are no extensions, which positively affects the service life and precision and best of all - they are not expensive, which I consider advantage of this solution.

Any good solution is dedicated, is a substitute for each other which forces the manufacturer some solutions that do not go hand in hand with usability -to however, requires an investment.

It applies to any device, not just the stove, examples can be multiplied.

5. How furnace is insulated?

An important parameter is the insulation of the furnace, how check if the heater is well insulated? Contrary to the colloquial thinking - insulation thickness is not the most important, the producers who invoke such an argument does not know what they are talking. If you managed to do a centimeter vacuum insulation and reduce infrared radiation, such isolation was by far more effective than even a meter of poor wool.
Determining parameters will be the thermal conductivity, which consists of insulating characteristics of the material used and the design. Even if the insulation is a lot, and in the inside are thermal bridges to the outside walls, and so will be hot.

Well, how to check if this can not be verified on the basis of parameters of the offer?

You need to touch it, and the case is clear, therefore, invite you to us for testing.
We have thermal cameras and professional measurement instrumentation, which allows us to exclude such basic school mistakes.

Do you know that...
The air in the still is a better insulator than the mineral wool.

I read somewhere on the internet opinions of one producer, which stated that if not blindness upper rails by heat escapes and the furnace is then improvident.

Well, the truth is that the cost of heat build-furnace is a fraction compared to the cost of even the cheapest paint, for example, the cost of heat build electric furnace with dimensions W1200 H1800 D3000 is some 2.5$, considering that in this way I find no sense.

We go further, however, since the rail section 70x70 escapes the heat, I ask how much heat escapes through the hole in the furnace the size of 1200x1800 means 440 times the surface area?

Knowing the physics, we know very well the principle of the air curtain - none furnace with automatic conveyor other than the power-and-free does not have a door, because the elements still to enter it and you can't close it yet. Despite the alleged losse ssuch this installations are cheaper than manual.

In the case of our standard oven stationary internal circuit it is so strong that it does not allow the escape of heat from the chamber.

Furnaces have temperature parameters such:

a) Temperature hysteresis which is a curve of the oscillation around the setpoint temperature.

Example, the desired temperature is 180 degrees Celsius, turning on and off the heating does not increase or decrease the temperature, set temperature is maintained throughout the process of heating and is not oscillating.

For hysteresis which has two levels; state high is 182 degrees Celsius while the low state 178 degrees when set to 180 degrees Celsius

For perfect furnace, hysteresis is 0.

How to deal with it?

Maintaining the best hysteresis is possible in the case of using a heating unit which has a low thermal inertia. The greater the power of the heat exchanger / single heater, the greater his / her inertia.

b) Dispersion of temperature in the furnace, is another parameter which is a deviation from the extreme temperatures in the furnace, for example, the desired temperature is 180 degrees and the difference of 10 degrees in one end of the furnace can be 170 degrees, and the second 190 degrees, this is a dangerous limit which may cause coating defects.

How to deal with it?

Air circulation should be deliberate, purposeful and adjusted. The fan itself does not mix evenly the air in the chamber if the circuit is badly adjusted, especially as it has no regulation at all.

c) The difference between the measured temperature and the average temperature in the chamber

This is another parameter that can be misleading. We deal with it by introducing developed by our MTS system which through the use of multiple sensors instead of one knows exactly where and how much temperature is located.

In the standard design is one sensor, himself the answer - what is the statistic of one measurement?

If these parameters fail, the stove can greatly cheat temperature, so it is important to counteract each of them.

Opracowanie Romer P.P.