Induction Heating

Precious Plastic Machine Development
#1

Hello everyone,
I have been working with a local high school over the last few months building the extrusion machine. My portion has been to modify the resistive heating system into an inductive heating system.

In theory this will allow for a more efficient system and potentially easier to source although the last is dependent on how much salvage you’re willing to do.

In addition I have experimented with a single heating coil with progressively spaced coils so that one coil could have two heating zones.

I am wrapping up the project and will share all my designs and data in the coming weeks but was hoping to hear thoughts from the community for my final presentation(this was a capstone project for my EET degree).

I did a couple searches but did not see any other inductive heating versions so if anyone knows of one I’d be interested in hearing about that too!
Thanks for everyone’s effort into this project!
-gary

#2

Interesting. Looking forward to your results.
Why would it be more efficient than the resistive heating? For the extrusion machine, there is a small loss due to heating up the thermal mass of the band heaters, but otherwise the energy ultimately goes into the tube, auger, and plastic. That is still true for the inductive design no?
The press oven is a different story

#3

Heating the auger sounds interesting though I’m not sure how one controls it. maybe just open loop based on trial end error.

Once the barrel reaches the control temperature, I think the external convective losses and the conduction loss to the cold side are both probably insensitive to how it was heated, especially with some insulation on it.

Great project though and good luck with your presentation.

#4

Inductive heating is a bit more efficient as the heating actually occurs in the tube itself not the coil. With a bit of tuning it is in theory possible to cause the auger itself to heat which means the heating radiates out and 100% of the thermal energy moves into the plastic rather than radiating into the air/environment around the tube.

I would not say that this is a crazy level of efficiency gain but it is more efficient.