Making induction heated extruder

Standard extruders are heated by simple resistive heaters and you basically need to push enough 12 or 24 V DC electric current trough a resistor and simple MOSFET.

Induction heated extruders would have many advantages over them: faster heating up, no high temperature insulation is needed and less thermal mass. All of this could make induction heaters light and fast.
Main disadvantage is the more complex electric circuits needed to power it and more complex control unit since it is using much higher voltage and hundreds of kHz AC.

RepRap builder SB made a post about his induction heated extruder, here is his work and schematics:

Induction heated extruder, you can clearly see the induction coils

The induction coil heats the sleeve made from mild steel (ferromagnetic) while the stainless steel is not heated directly because it is not ferromagnetic.

The electronics schematics are not yet available.

You can get more details here:

http://builders.reprap.org/2009/05/induction-heating.html

To get more information on induction heating you can alos check related project of induction heated solder iron:

http://www.eevblog.com/forum/projects/diy-metcal-13-56-mhz-rf-supply/

First post about induction heated extruder on RepRap forum:

http://forums.reprap.org/read.php?2,481721


Bulent made the extruder and posted a YT video of it working (bt videos are not in English):




Here is a video showing more details, but again language is not English:




As someone noticed in the comments, it would be interesting to see the induction extuder based on filament with metal particles where induction heats the filament itself. Then you could reduce the mass even further.