3

As far as I understand, induction cookers transfer current (via eddy current) to the pot which heats up due to its resistance to the current. Because of this, induction pots and pans should be ferromagnetic for the eddy current to work. Therefore magnets should stick to the pot.

Now here's the thing. I was able to use a non-magnetic pot for cooking. All parts of the pot (screws, handle, body, cover) doesn't stick to magnets and yet it works when it's not supposed to be. I am not sure what alloy the pot has nor proof marks for that. The magnets I have are a neodymium and a ceramic one.

I only used the pot to boil instant noodles. My mother was surprised by this.

Looking this up, I can't seem to find an explanation. Any ideas?

Thank you and stay safe~

[EDIT] I tried hanging the magnets on a string and slowly held the pot closer and closer, no reaction.

2
  • I have a non-magnetic pan that heats up on my induction range. It is a stainless steel stock pot and magnets will not stick to it but the pan will heat up as quickly as my induction cookware. Frankly I was amazed it worked because I was demonstrating to someone how non-magnetic cookware wouldn't work (boy did I feel silly).
    – Mr. Joe
    Feb 8, 2022 at 12:35

5 Answers 5

5

It is likely that it was a different metal that supports inductive currents, such as aluminium.

The problem with aluminium is not that it can't create inductive current and heat up. It can, but it is rather inefficient on induction. Also, it has a very low melting point, so with thin aluminium, you risk melting it.

Many induction units have artificially added constraints to not work if they don't sense a ferromagnetic pan of a certain size, aswhich is a safety feature. Maybe yours doesn't, and so you were able to heat your pot. This doesn't make it a good idea to continue - even if you don't run into trouble with melting, you are losing much of the advantages of induction cooking.

6
  • Thank you for the reply. So aluminium can still have induction currents despite not being magnetic? Also while I admit the cooker is a cheaper brand, it still has a safety feature where it would stop working when it doesn't detect a payload on top of it. But still,I will probably stop using the said pot, for risk of melting and also the inefficiency. Mar 18, 2020 at 10:36
  • 2
    Stainless steel also isn't always magnetic (depending on the exact mix of metals being used)
    – Joe
    Mar 19, 2020 at 7:40
  • 1
    Heating via eddy currents works in any conductive material, so also in aluminium. But in typical induction cookers, a significant portion of the heating does not come from eddy currents, but from hysteresis (changing the magnetization of the material at a high frequency), which contributes somewhere between <10% and 30% of the heat depending on the source you trust. And the latter mechanism only works in magnetic materials. Aug 20, 2021 at 8:56
  • @MatthiasBrandl interesting! I must admit that electromagnetics is not my strong suit. Do you think that the answer is incorrect, and that eddy currents in aluminium shouldn't have been enough to bring water to boil, or is it an additional detail which is compatible with the answer?
    – rumtscho
    Aug 20, 2021 at 9:05
  • Hm, the answer is incorrect in one respect, as you can create inductive currents in aluminium. It would heat up a bit slower than a magnetic pot because of the lack of hysteresis heating, and probably not work at all on a cooker that has "pot presence detection" based on magnetism. But without a direct comparison, the different rate of heating would be difficult to notice. Aug 20, 2021 at 10:50
2

I have seen this too. It's because "Only pans that magnets stick to can work with induction hobs" is an oversimplified way to describe induction hob compatibility. Manufacturers prefer not to make the explanations more complicated. But there are some exceptions where magnets won't stick to the pan, yet the pan works on induction stoves. One example: stainless steel is an umbrella name. There are many different stainless steel alloys. AISI316 grade stainless steel is austenitic, which means it is non magnetic. But it is food safe and works with induction hob.

1

Are you sure the range is truly induction? Perhaps it's an electric glass-top model instead- which works wonderfully with non-magnetic cookware.

2
  • There are various types of range which have glass on top and are powered by electricity… which type did you mean?
    – Sneftel
    Aug 19, 2021 at 21:23
  • 1
    @Sneftel: ‘glass top’ was just a style of resistive for a long time before induction came along. They’re very popular as they don’t have the cleaning issues of resistive coil cooktops, and can have more varied sizes of heating elements.
    – Joe
    Feb 8, 2022 at 13:30
0

I think the problem is that the magnet you tested your pots was too weak. I tested my pots with a NeFeB cherry sized magnet and it didn't respond, even though those pots heat up just fine on the induction stove. But when I took a powerfull NeFeB magnet the size of half a bank card and 1 cm thick, the pot hanging on the dryer shook weakly next to this magnet. Apparently even that weak magnetic property is enough to heat.

0

Another factor is that non-flat bottoms are less likely to heat, via any of the physical mechanisms as contact is different.

As some of our pots aged and distorted slightly they took longer to heat up.

In some cases they now don't trigger the sensors properly any more at all. Then the induction element sometimes turns itself off, which didn't happen before when these pots were new. You can use them on some bigger elements or when well filled with water.

Some better quality heavier pots have behaved better for us as they aged and they still heat just as well, for them the non-stick linings wear out first.

Cleaning every speck of cooked grease off the outside helps too.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.