Building a NEO Magnet Magnetizer

In summary, the conversation discusses the challenges of building a NEO magnet magnetizer for RC motors and the issues with maintaining magnet strength in Brushless motors compared to the older brushed ceramic magnet motors. The individual is seeking help in designing a magnetizer and fixture to hold the arm and mentions the difficulty in removing and replacing the magnets. There is also a warning about the dangers and high costs involved in building a magnetizer for NdFeB magnets.
  • #1
EddieO
2
0
I am looking to build a NEO magnet magnetizer for RC motors. Currently we are having issues with the motors losing magnet strength after they are run. The rotors to replace are $30+. In the Old days, we ran brushed ceramic magnet motors. With these, we had a magnetizer to simply zap the motors back to strength. Now, the entire hobby has switched over to Brushless motors, which all use a sintered NEO magnet on the rotor.

The rotors look like this. Half is magnetized to the south, the other to the north.

novakrotor.jpg


Now a few specifics...

I am electrically inclined. I've assembled numerous projects from the ground up, including a ceramic mangetizer, LipO battery chargers, and more. I am an extremely good at soldering and I very safe in all my projects.

I know that I will be playing with large amounts of voltage and amperage...

The rotors can be removed from the motors very easily. The magnet cannot be removed from the shaft.

I am in need of help designing the magnetizer along with the fixture to hold the arm. If the unit can be even somewhat portable, that would be a big plus.

Any help would be great.

Later EddieO
 
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  • #2
Great photo, but where is the magnet? Is it the larger metallic cylinder on the lower image?

Have a look at this thread which is from last year and which went on for about 4 months.
It may give you some idea of what is involved.

https://www.physicsforums.com/showthread.php?p=2286084#post2286084


Neodymium magnets are very difficult to magnetise and should not demagnetise as easily as yours seem to be. Are they getting very hot?
 
  • #3
Yeah, that would be the magnet...they are impossible to remove without destroying them.

The motors get pretty hot, which along with the rotational speed (up to 70k rpm), is more than likely causing the loss in magnetic strength.

There are multiple commercial systems out there that can do it, I am just not going to pay $20,000+ for something that has less than $2000 in parts...most of the units also have a ton of features, which I don't need.

Later EddieO
 
  • #4
The system has a lot more than $2000 in parts, and I honestly recommend you don't try it. Just buy a new rotor, and start cooling it, or buy one that uses SmCo magnets.

With that said, a magnetizer normally consists of a bank of quick-discharge capacitors, roughly the size of 1-gallon cans. A typical magnetizer in industry has a bank that is about 10x3x3, or 90 such capacitors, to get to a final capacitance on the order of 10-40 mF. You then have a set of transformers to convert incoming voltage up to the limit of the caps, (2-5kV), and a set of thyristors to dump the juice into a coil. (or, more likely for your rotor, an array of coils). There is also an attendant set of controls. The coils are typically heavy gauge wire wrapped around a laminate core, and potted with water jackets.

I have cleared $2000 RE-building just a coil, when I already have heavy gauge wire, laminates and plates on hand. This is ignoring that I already had the magnetizer and chilled water system.

Again, I'm not saying it can't be done - I'm saying it's unlikely to make economic sense, it costs more than you think, and even you are safe around electricity, you are running the risk of an "instantly fatal" accident, not a "unpleasantly shocking" accident. NdFeB magnets have drastically higher coercivity than the ceramic magnets you remember - you are truly in a different zone here.
 
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Related to Building a NEO Magnet Magnetizer

1. How does a NEO magnet magnetizer work?

A NEO magnet magnetizer works by passing an electric current through a coil, creating a magnetic field. This magnetic field is then used to magnetize a NEO magnet by placing it inside the coil and slowly decreasing the current. This aligns the magnetic domains within the NEO magnet, creating a permanent magnetic field.

2. What materials are needed to build a NEO magnet magnetizer?

To build a NEO magnet magnetizer, you will need a power source, a coil of wire, a switch, and a capacitor. The power source should be able to supply enough voltage and current to magnetize the desired NEO magnet. The coil should be made of copper wire and shaped to fit the NEO magnet. The switch is used to turn the current on and off, and the capacitor helps control the current flow.

3. What is the process for building a NEO magnet magnetizer?

The first step in building a NEO magnet magnetizer is to construct the coil using the copper wire. The coil should be shaped to fit the NEO magnet and have a few layers of insulation to prevent the wire from shorting. Next, connect the coil to the power source, switch, and capacitor in a series circuit. Then, test the circuit to ensure it is functioning correctly. Finally, place the NEO magnet inside the coil, turn on the switch, and slowly decrease the current until the magnet is fully magnetized.

4. What safety precautions should be taken when building and using a NEO magnet magnetizer?

When building and using a NEO magnet magnetizer, it is essential to take proper safety precautions. The high voltage and current used to magnetize the magnet can be dangerous. It is recommended to wear protective gear such as gloves and safety glasses. Additionally, ensure proper insulation on all wires and components to prevent electric shocks. Finally, always follow proper procedures and instructions when operating the magnetizer.

5. What are the advantages of using a NEO magnet magnetizer?

The main advantage of using a NEO magnet magnetizer is that it allows for precise and controlled magnetization of NEO magnets. This results in stronger and more consistent magnetic fields, making them ideal for various industrial and scientific applications. Additionally, building a NEO magnet magnetizer is cost-effective compared to purchasing one, and it provides a better understanding of the magnetization process.

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