# Burning up too many heaters

#### Gdrumm

Joined Aug 29, 2008
684
Where I work we make paper cups. The ones we are having trouble with use electric heaters, with compressed air blown over the heaters to create forced hot air, that blows out of small holes in a diffuser.

That forced hot air melts a poly coating on the paper, and that part of the cup is then joined to another part of the cup which was heated the same way.

We frequently burn up these heaters because mechanics either turn the heat up too high (1250 degrees), or turn the air down too low (500CFH).

I am looking for some training material I can use to explain the physics behind air flow through a restricted nozzle, and the interrelationship between the major factors, heat, air flow, air volicity, dwell time (machine speed), diffuser gap from the diffuser to the paper, and etc.

I want to be able to explain how it should work, and what it's peak limits are, to prevent burning out the heaters.

If anyone knows of a link or website which has something similar, I would apprecaite the help.

Thanks,
Gary

#### mcgyvr

Joined Oct 15, 2009
5,394
You can try to teach them till you're blue in the face.. They don't care and will just turn it up again. You should provide a method to prevent easy adjustment. Like locking the control box or whatever.
Or better yet make it only adjustable a certain bit so that no matter what you can't cause damage.

We had a similar situation here with a batch oven used to dry ink from a silkscreening process. The operators kept turning up the heat so the parts would dry faster which would cause the ink to yellow. We simply installed a new dial with the ability to prevent the knob from being turned up all the way.. Problem solved.

#### joeyd999

Joined Jun 6, 2011
4,370
To *solve* the problem, a PID loop controlling the heater temperature would provide best results. You could use the heater resistance as a measure of temperature, and the heater would maintain the same temp regardless of airflow.

My 2 cents.

#### DickCappels

Joined Aug 21, 2008
6,300
In other words, "no". I suspect that nobody has seen all of the topics you mentioned in a single presentation or tutorial. You would probably be best pulling together information from these diverse topics yourself.

#### crutschow

Joined Mar 14, 2008
24,709
How about adding a temp probe to the heater and using that to shut off the heater current if the temperature becomes too high?

#### Wendy

Joined Mar 24, 2008
22,134
Lock the controls down, then provide an on/off switch instead.

#### goodinin

Joined Feb 5, 2012
2
You would probably be best pulling together information from these diverse topics yourself.

#### gerty

Joined Aug 30, 2007
1,276
What is the voltage of the heaters? Can you use a heater element of a higher volttage and get enough heat from it to do your task?
In other words, if you have a 220 volt system, would a heater rated at 440 volts give you enough heat? The reason for this is a much longer element life since it would be powered by a reduced voltage.