Just sharing a bit of information.
Some time ago I was tasked to control the temperature of a heat plate for a foil embossing letterhead printing press. The thing about the heat plates is the heat rise is very much time delayed to the heat registered by the thermocouple. What I was able to use was a Temperature Process Controller by Omron.
What is real nice about this unit was the auto self tuning feature. To set this self tuning in motion you would start with a cold plate and the unit would turn the heater element on and off automatically until it overshot the setpoint it then would let the plate cool to under the setpoint and do this 3 or 4 times until it understood the relationship of heat rise/loss and time.
Then the unit would be done programing and on the next process run it would ramp right up to the set point you have entered and do a great job holding the setpoint by using the knowledge of the rate of heat loss and heat rise over time .
I know this is way over kill for us but I just wanted to share my dream for my Christmas gift this year.
http://www.grainger.com/Grainger/items/3MM67http://www.grainger.com/Grainger/items/3MM66
