Induction Foil Iron vs. Aluminum

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Watson
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Hey everyone.

This question revolves around induction/cap sealing - or just induction heating in general.

Does anyone have an idea of why aluminum foil is used in induction sealing vs. using something that is magnetic, such as iron foil? My initial thought is simply aluminum foil being significantly cheaper, but I am curious is someone could answer this from an engineering perspective. Does aluminum foil heat more efficiently than magnetic iron foil?

Thanks guys!
 
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Good question. My initial thought is that aluminum would be much more difficult to heat with induction, as iron typically has a much higher permeability. My money is on the cost.
 
stinsonbr said:
Good question. My initial thought is that aluminum would be much more difficult to heat with induction, as iron typically has a much higher permeability. My money is on the cost.

Mine as well. Aluminum has higher thermal conductance than iron/steel, and as a the foil itself is much smaller than the skin depth of aluminum, the resistance is bumped up significantly. That being said, the skin depth in magnetic iron foil should be similar when you take into account the permeability. Stumped on this one.