how to strengthen magnet

[grandmasteralok]

Hi... i race to y cars using brushced / commutator type motors... i've heard that there are "zappers" which strengthen the magnets... can anyone help me how i could strengthen my magnets without using zappers??? i tried the electromagnet theory, i wrapped a wire around the motor and connected it to a 9V battery... but i am not really sure if it has any effects at all...

your help will be very much appreciated... thanks.

 

[Optikon]

Hi... i race to y cars using brushced / commutator type motors... i've heard that there are "zappers" which strengthen the magnets... can anyone help me how i could strengthen my magnets without using zappers??? i tried the electromagnet theory, i wrapped a wire around the motor and connected it to a 9V battery... but i am not really sure if it has any effects at all...

your help will be very much appreciated... thanks.

well, when you wrapped wire around it and connected 9V battery it likely did not produce much field strength. How many turns did you have and how much resistance is in the wire? Also if your 9V battery was the typical types used in portable electronics, then it has a lousy internal resistance and cannot really provide a strong current.

Also consider that if you heat the material first, it will be easier to magnetize. Setting the magnetic domains in thermal motion makes it so that less energy is required to orient them with an external field.

Heat up your material, blast it with as high of field strength as possible (use a real power source not a 9V & fat wire - lots of turns) keep the field enabled while the material cools then check how magnetic it is.

 

[audioguru]

You don't want to magnetize the motor. You want to magnetize the 3 magnets inside it.

 

[grandmasteralok]

well, when you wrapped wire around it and connected 9V battery it likely did not produce much field strength. How many turns did you have and how much resistance is in the wire? Also if your 9V battery was the typical types used in portable electronics, then it has a lousy internal resistance and cannot really provide a strong current.

Also consider that if you heat the material first, it will be easier to magnetize. Setting the magnetic domains in thermal motion makes it so that less energy is required to orient them with an external field.

Heat up your material, blast it with as high of field strength as possible (use a real power source not a 9V & fat wire - lots of turns) keep the field enabled while the material cools then check how magnetic it is.

can i instead use a 13V regulated power supply??? will it not short because i will be connecting both ends of the wire to + and - poles of the power supply... thanks for the feedback... i used a stranded wire... i think a little thicker than the wires used in 9V battery connectors...

 

[grandmasteralok]

You don't want to magnetize the motor. You want to magnetize the 3 magnets inside it.

yes... indeed... that's what i wanna do... only that i am not sure how many magnets are inside... the motor is for the mini 4wd so it's fairly small... does it matter how many magnets are there???

 

[Glyph]

It might be more straightforward to purchase neodymium magnets (ebay has loads of them) and replace the magnets inside the motor with those magnets. Obviously you have to get the shape and orientation right for this to work.


The problem with simply applying an electromagnetic field is that you have to apply the field in the same direction as the magnet you're trying to strengthen. Simply wrapping the motor with some wire and running a current through it will at best magnetize only one magnet properly while at worse reverse the polarity of the other magnets. you'll need to take apart the motor and apply the field to each magnet seperately.

As optikon said heating the magnet and then cooling it while the field is applied will help to magnetize it. but in order to obtain maximum affect you'll need to heat the magnet to above its "Curie" temperature to reset all the magnet domains.

Another issue is that the material the magnet is made of will have a saturation density above which it cannot be magnetized further. Neodymium magnets are magnetically the densist commercially available magnets. Its doubtful that you can magnetize your magnets to a much higher degree than was set during their manufacture unless the motor you're using is very old and its magnetism has decayed.

You can get around the saturation problem by using an electromagnet instead of permanent magnet. so while the motor is running the electromagnetic field is constantly applied. The more current you apply the stronger you're motor will be... But at this point you're reengineering you're motor.


Magnetic replacement is probably the most viable option for increasing your motor strength.

If you're really hellbent on reengineering you're motor for enough strength and speed to lift a model helicopter then type in "Cd-rom motor" into google and you'll find a community of individuals that modify Cd-rom motors for that task.

 

[Sceadwian]

The magnets inside the motors are likley already neodymium. but replacing them with fres magnets won't hurt, those motors get a little warm, and heat destroys the magnetisim over time. Also, no matter how strong the magnets are the electric field which creates the other end of the magnetic field which actually creates the force is important. Perhaps a custom winding, very difficult though on that small of a scale, you almost need a microscope to do construction.

 

[Dean Huster]

Replace the motor with a .049 IC model airplane engine and add electronic controls. Great design challenge, don't have to worry about magnets and your competition will be blown away (especially if you leave the propeller intact).

Briggs & Stratton "charges" the magnets in the flywheel (the uncharged magnets are cast into the wheel and then machined down along with the wheel) without all that heating-cooling foo foo. You guys aren't going to help those magnets out a bit with those dinky power sources. This project requires enough amperes to make normal wiring melt.

Dean

 

[grandmasteralok]

thanks for all the replies... but i it's illegal to open the motor, so it's not an option for me to open it... to be precise, i am using tamiya mini 4wd motors, manufactured by mabuchi motors company...

Glyph: you said that worst case would be reversing the polarity of the magnet... how would i know if this has already happened??? will it help if i run the motor while electromagnetizing it???

 

[Hero999]

Why do you want to increase the magnetic field?

It will increase the torque but reduce the speed; is that what you want?

You'll get more acceleration but a slightly lower top speed.

 

[grandmasteralok]

i didn't know that strengthening the magnets would result the motor to reduce top speed... i am aware though that it would increase the torque... regardless, i still prefer to strengthen my magnets... since having low torque means that the motor would lose speed significantly in entering corners and climbing slopes...

so yes, i would want a higher torqued motor...

 

[Styx]

Why do you want to increase the magnetic field?

It will increase the torque but reduce the speed; is that what you want?

You'll get more acceleration but a slightly lower top speed.

exactly. Higher magnets means higher Kt but also higher Ke, which means you will run out of forcing volts faster as the backEMF will be higher for a given speed

if you do increase the magnets you will have to do funky stuff like field-weakening to regain high-speed performance. OR up the voltage supplied

 

[grandmasteralok]

yup... it's fine with me... i could gamble from losing top speed in exchange for higher torque...

 

[john1]

If they will not give you permission to take their motor to bits,
then you are not going to be able to deal with each magnet separately.
You cannot do this to all the magnets while they are in the assembly.

It may very well assist the process to heat the magnet under attention
but i don't think it is necessary.

As 'Dean Huster' has already said ... "this project requires enough
amperes to make normal wiring melt",
and he is quite correct of course,
however i think that fortunately the current only needs to be present
for a short time, thats why its called 'zapping'

You will not get the sort of current you want unless you put several
motor car batteries in parallel. You would need some serious form of
conductor, and each extra turn you add will increase the your burst
of magnetic field.

On the down side ...
As 'Glyph' has said, the material used by the manufacturers will have
been chosen to suit their intentions, and it will almost certainly
already be magnetised to saturation, or near saturation.
You could possibly purchase replacement magnets of higher strength,
but this brings other problems with back emf and so forth.

One possibility is that you could increase the cooling somehow, and
simply push the motor harder by overdriving it a bit.

Again, if you cannot take it to bits, then you cannot deal with the
magnets on an individual basis.

And if you are willing to lose some top speed,
in exchange for some higher torque,

Then altering the gearing, might be easier than tweaking the magnets.

Best of luck with it, John

 

[audioguru]

The magnets are arranged in a circle so it is not possible to use an electromagnet on the outside to increase or to decrease their magnetism.

Even if it is possible then you flip a coin to determine if you have the correct polarity. You would have the same odds of decreasing the magnetism as the very slim odds of increasing it.

 

[mneary]

but i it's illegal to open the motor

What does this mean? Are you in a competition where you've agreed to use a standard motor.... and you're trying to make undetectable modifications?

If the motor is defective, replace it. If you want an edge, get several motors and test them.

 

[john1]

but i it's illegal to open the motor

This poster could be from that place where the 'Motor Police' are
still in control.
You can see his nervousness has come through in his writing, as he
was writing about opening the motor, he glanced over his shoulder
with dread, and it came out like a stutter.

In that place, all motors have to be registered with the 'Motor Police'
and anyone found tampering with the 'secure seal' on any motor, will
be sent to the magnet mines for correction therapy.

He has obviously heard the stories about the magnet mines ...

 

[grandmasteralok]

with all due respect, john1... i don't do cheating... which seems you did imply... and we do not use standard motors... we can choose any motor but not to open or tamper it in any way... they allowed usage of oils on the commutators, and any other tweak as long as the motor is not opened...
and please, do not judge my posts... who are you to say that i am nervous or what... besides, i first heard of the "magnet mines" from YOU... so what are you saying that i "obviously" heard about it somewhere else... please, if you are to insult anyone, try doing it to yourself... my post is to seek help, and people with attitude like yours are very much not welcome... you may have the answer, but i would try harder asking someone else rather than wasting time with people like you...

 

[Nigel Goodwin]

with all due respect, john1... i don't do cheating... which seems you did imply

So you don't do 'cheating', you simply want to gain an unfair advantage without being detected? - interesting play on words!.

However, I don't see as it's possible to make the magnets any stronger with out removing them from the motor - I wouldn't even swear it's possible to do so if you DID remove them first? - I would expect such magnets to already be as strong as the material allows?.

 

[audioguru]

Are you allowed to use a battery with a higher voltage?
If you are not allowed to use a battery with a higher voltage then do the rules say that you cannot boost the voltage of the exising battery?

Then the motor will be very powerful and the car might smoke. You will need to replace the motor after winning each race.