Oven Conversion to Powder Coating Use?

[RonRock]

I find with this type of set up they tend to over shoot a lot. If you set at 400 does it eventually settle out and hold?

I think that it would. To be honest I have been so busy trying to get the temperature to set properly that I haven't given it a chance to settle out.

 

[RonRock]

These types of elements just don’t respond quickly. Been a while since I’ve done this on that type of system. I would suggest setting the Intragral setting Way higher. Not like 10, like 8000. Or just set to 300 and when it starts to stall set to 400. Otherwise you need a ramp controller that you can set to heat up more slowly.

I'll give that a try tomorrow. There is a lot of room in the setting range 0-9999.

 

[no704]

I have a tube furnace that it’s elements also respond slow, I’ll usually set it about 100 degrees less than I want. It will over shoot about 80 degrees then I reset to desired temperature. But that’s usually 800 - 1000 c

 

[no704]

I think that it would. To be honest I have been so busy trying to get the temperature to set properly that I haven't given it a chance to settle out.

Let it settle. If it’s still way out then make adjustments.

 

[walta]

These types of elements just don’t respond quickly. Been a while since I’ve done this on that type of system. I would suggest setting the Intragral setting Way higher. Not like 10, like 8000. Or just set to 300 and when it starts to stall set to 400. Otherwise you need a ramp controller that you can set to heat up more slowly.

Would I be correct if I said the adjustments you are describing are used in the manual mode and the auto mode should learn and set them for him if he lets it run?

Walta

 

[walta]

I have a tube furnace that it’s elements also respond slow, I’ll usually set it about 100 degrees less than I want. It will over shoot about 80 degrees then I reset to desired temperature. But that’s usually 800 - 1000 c

I like the lower my set point idea while it is learning. Especially if you are afraid, it could over shoot and exceed the limits of your safety thermostat.

Yes, let it run it will take a few dozen cycles for it to tune itself. Yes, it will way over shoot on the first cycle and it will over correct and drop below the set point each cycle the error will get smaller as it learns and adjusts. The next time you power it up it will remember what worked but the first cycle often has some overshoot from a cold start.

 

[RonRock]

My first settings, found on Youtube video by a guy that did a very helpful video on the Inkbird PID. Although he uses them for distilling, so I figured that the settings would be incorrect for an oven element. But it was a place to start.

P-10
I-540
D-200

Those weren't even close. I failed to record the temps, but it was not good results.

So I made my attempt at using Auto Tune. I first set the temp at 300*F and ran AT several times. AT will run through several cycles then the PID goes into PID mode.

300* F Auto Tune

P-10 P-7 P-7 P-7
I-62 I-75 I-74 I-73
D-15 D-18 D-18 D-18


400* F Auto Tune

P-7 P-6 P-7 P-8 P-7
I-57 I-60 I-60 I-58 I-60
D-14 D-15 D-15 D-14 D-15


I did not keep record of the temps on these AT's but they were all higher than setpoint. As I recall 15* F or more.

So then I decided to try something. I set the D at 0 and set the P,I based on what I saw from the AT.

400* F setpoint

P-7 P-8 P-9 P-9
I-60 I-60 I-60 I-60
D-0 D-0 D-0 D-0

416.9* F high 410.5* F high 412.7* F high 413.2* F high
396.6* F low 396.7* F low 396.8* F low 396.7* F low

Still no joy. So I started playing with the I setting and left the P at 8.

P-8 P-8 P-8 P-8 P-8
I-120 I-220 I-20 I-40 I-10
D-0 D-0 D-0 D-0 D-0

410.6* F high 416.7* F high 417.2* F high 416.4* F high 417.8* F high
397.0* F low 396.5* F low 396.4* F low 396.8* F low 396.5* F low

I then tried P-7

P-7 P-7
I-20 I-120
D-0 D-0

418* F high 416.9* F high
396.5* F low 396.8* F low


So I based my attempts at what I found by running the Auto Tune. My settings all stayed pretty close to the temps that the AT resulted in.


I am at a point that I don't know enough to make a change and have an understanding of what to expect by the change. I was hoping that the AT would give me an indication of a place to start, if not actually auto tune to work as expected. I have watched several videos on what PID actually do, so now have somewhat of an idea. But their explanation always shows graphs that show the curve created by the settings. I can't see how to correlate that to an oven.

 

[RonRock]

Sorry about the formating. I had it done so that it was understandable. For some reason my formating was changed when I posted. Damn irritating!

Made the F'in thing unreadable.

 

[no704]

From my very basic understanding and trial and error. If the heating elements are sunk in a mold or liquid the d setting is more important. In an open air like an oven the I setting will have more of an effect. It’s a bit complex but larger settings will usually result in obvious differences. I’ll usually use a separate thermocouple in the desired area

 

[no704]

Would I be correct if I said the adjustments you are describing are used in the manual mode and the auto mode should learn and set them for him if he lets it run?

Walta

Um maybe I’m a bit slow. I like to use the auto learn mode and than twek from there. Haven’t tried it but I’ll bet the auto mode does better from starting closer to desired temp

 

[RonRock]

Um maybe I’m a bit slow. I like to use the auto learn mode and than twek from there. Haven’t tried it but I’ll bet the auto mode does better from starting closer to desired temp

That is what I was thinking as well. Run Auto Tune to get a baseline to start from. Today I will try bumping the I setting way up as you suggest.

 

[RonRock]

Well I spent yesterday doing more testing. I Bumped the I setting up to 8,000, 8,500,9000 and tried those at different P settings 6, 7, 8, 9, even tried P-3 at I-7000. Nothing even gets close to holding the high temp.

Today I'm running Auto Tune again. The AT runs for several cycles (maybe 3) then sets the PID from Auto Tune to PID and sets the settings that it has came up with. After a couple tries with AT today it came up with P-8, I-56, D-14 Temps ran from 419F high to 396F low. Next At came up with P-9, I-49, D-12 temps of 416F, 415F, 415,F high, lows I missed several but 396F average.

I'm starting to get concerned about the overtemp fuse. I don't want to break it during my testing. I can not find the temp rating for it. Any idea of what temps typically are for these? I'd guess that it is probably 550* F. Pure guess.

It is an FSP 4451442. Picture is same as mine,

 

[whateg01]

I think you're putting way more effort into getting the temperature perfect than I would. Powder coating isn't rocket science. Most of the powder I use says 375F, and that which doesn't say gets baked at 375F and has never been a problem for me. If the temperature varies a little it's not going to hurt anything. You just don't want it to runaway.

 

[RonRock]

You are probably right about that. I have no experience with powder coat. So I have no idea of the acceptable temperature variables. But it sure seems to me like I should be able to get closer than a 5*- to a 15*+ temp. Thats a 20* swing. From what I've read I should be able to get closer than that. But as you said, maybe I don't need to. IDK.

 

[no704]

That will be fine. Put your temp probe in an unmodified oven and watch that.

 

[walta]

I'm starting to get concerned about the overtemp fuse. I don't want to break it during my testing. I can not find the temp rating for it. Any idea of what temps typically are for these? I'd guess that it is probably 550* F. Pure guess.

If the oven had self-cleaning the over temp cut out would be above 900°F


Walta

 

[RonRock]

If the oven had self-cleaning the over temp cut out would be above 900°F


Walta

It did have self clean. Thank you.

More testing done yesterday. Still no joy. I started by setting I to 1 lowest it will allow. D-0. Then started changing my P first at 1, then 2, 3, and various settings. Eventually I jumped to 9,999 and it seemed to be the best. Although nowhere in the various settings was I able to get the temperature to drop below 396. Most times it was at 397*F. and the high was never less that 410 and usually 413-415*F. So no matter what P setting I try I am unable to get a curve that has setpoint in middle.

I then set P @ 9,999 and started with I same routine. Same results. Eventually found best results with I @ 8,500.

Not very good control. 397*-412*F. Frustrating.

I think that I will swap PID's today. I have a very good (expensive) one that I did not want to "waste" on this project. Actually not like it's made of gold, $130.00 PID but better than the Inkbird. I'm hoping that it has a better Auto Tune feature.

Seems odd to me that no matter what setting I set there is no drastic difference in the temps. It is almost like the PID isn't really changing anything. Makes it very hard to see what to do.

 

[RonRock]

Well nothing is as simple as I think it will be. I swapped PID's to my "better" one. But now I'm afraid to power it up. I can't figure out how to set it up to drive the SSR. I don't see a DC voltage out. I do see that there is options for different types of outputs. But I don't know enough to know wich to choose, or if any will run an SSR. Sure seems like the PID should be capable of running an SSR.

The PID is an Automation Direct Solo SL4848-RR

https://www.automationdirect.com/adc/shopping/catalog/process_control_-a-_measurement/temperature_-z-_process_controllers/standard_temperature_controllers/sl4848-rr

Any suggestions?

 

[no704]

15deg swing for powder coat is more than acceptable. You are way over thinking this.