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  1. MagMike

    Electromagnet manipulating neodymium

    The electromagnets in your weblink are designed for maximum holding power while in direct contact with steel. Any air gap, 1 or 2 millimeters, significantly reduces their holding power. You'd be better served with a single, cylindrical piece of steel wrapped with wire. Ideally, the diameter of...
  2. MagMike

    Recommend a specialist for solenoid development

    Mark Juds wrote the book on this sort of thing (Amazon link): https://www.amazon.com/Practical-Magnetic-Electromechanical-Design-where/dp/1098333551 It's an excellent read. I'd recommend getting a copy of the book to get a sense of what is needed. He is on LinkedIn, maybe reach out to him there.
  3. MagMike

    Demagnetize parts close to magneto-elastic sensor in mid drive motor

    Demagnetizers aren't precision instruments. They produce an alternating magnetic field and as you slowly pull the part away, the alternating magnetic field sensed by the part gets weaker and weaker, eliminating much of the residual magnetizer. Effectiveness depends on many variables, but the...
  4. MagMike

    Magnetic Materials for moderately high temperature use

    Another option would be Samarium Cobalt, which can easily accommodate that temperature range. The density is 8.4 g/cc, a little higher than NdFeB.
  5. MagMike

    Magnetic Flux

    I recommend using the magnetic moment. Magnetic moment is the product of pole strength and magnet length. Cullity’s book describes it well: ‘Although pole strength and length are uncertain quantities individually, their product is the magnetic moment which can be measured precisely’. The...
  6. MagMike

    Welding: Using 304L vs 304L VIM/VAR

    DJI66: Did you intend this for the Magnetics Engineering forum? This might be a better question for the Welding forum: https://www.eng-tips.com/threadminder.cfm?pid=725
  7. MagMike

    PM hysteresis graph

    Clyde: If you need the measurement by a certified lab, I'd recommend Magnet Physics. They have a top-notch facility in Indianapolis: https://www.magnet-physik.de/en/
  8. MagMike

    PM hysteresis graph

    What type of magnet? It's straightforward for Alnico, most hysteresisgraphs have that functionality built in. I've run curves for various grades of Alnico with our equipment. It might be possible with a hard ferrite/ceramic. I don't think it could be done with SmCo or NdFeB.
  9. MagMike

    how to make an impulse magnet without removing the rest assembly

    Since you appear to be based in France, I'll recommend two companies in the European Union. Both of them make magnetizers that should work: In Germany, there is Magnet Physik: https://www.magnet-physik.de/en/ In Italy, there is Laboratorio Elettrofisico...
  10. MagMike

    material without hysteresis

    Arivel: You are looking for a superparamagnetic material. As far as I am aware, the only thing commercially available material are nanoparticles used for magnetic separation. I'm not aware of anyone selling them in bulk form suitable for a current sensor. Here is a link to one such provider...
  11. MagMike

    ASTM F2086/F1761

    Ben, I am still on A06 and enjoying it. I hope you re-join, we could use your expertise. I remember conducting Pass Through Tests on targets maybe 10 years ago. While it may not have been the best test, it was all the customer had available at the time and it did provide some quantifiable data...
  12. MagMike

    ASTM F2086/F1761

    I see both standards have been withdrawn, with no replacements. It would appear the committee overseeing them also saw problems with them. I'm not on the committee that developed those standards so I'm just speculating that 'magnetic conditioning' was done because the target will be magnetized...
  13. MagMike

    Rated temperature for magnets

    The rated temperature is oftentimes called maximum operating temperature and it is more of a marketing concept. I don't like it very much, but it has gained widespread acceptance amongst laypeople. That said, when the concept was introduced it was defined as the temperature when a magnet with a...
  14. MagMike

    Max temperature for Neodymium

    If the Neo magnets are nickel plated, I've found out the hard way that temperatures over 400 degF can cause microcracks in the plating, leading to corrosion. It's not normally a problem if you are talking about an injection molding situation where the magnet is exposed to an elevated temperature...
  15. MagMike

    magnetic properties of steels

    Most steel manufacturers won't guarantee magnetic properties of their product, but you can get a general sense from some of the books listed in this FAQ: faq340-1436 Hopefully your school has some of these available. You are going to have to adjust your expectations a bit to match what is...
  16. MagMike

    NdFeB magnetizing

    I don't believe so. Elevating the temperature will reduce coercivity but studies have shown coercivity doesn't play a huge role during magnetization for Neo. Assuming they are in the virgin state, a high coercivity Neo will fully magnetize at the same magnetizing strength as a lower coercivity...
  17. MagMike

    Electromagnet design

    Jpysam, In Case 2, if everything else stasys the same, the inner core will saturate earlier since it has less steel involved in the magnetic circuit. The total mmf will likely be less because of this.
  18. MagMike

    Electromagnet design

    Jpysam, Sorry, it sounded like you were designing a simple cylinder electromagnet. I didn't realize it was a round cup design. That said, the numbers for Case 1, with 88 kg appear reasonable, maybe a bit optimistic. I don't understand what you are describing in Case 2, can you provide a...
  19. MagMike

    Electromagnet design

    I modeled the first design in FEA and calculated 1.7 kg pulling force. For pulling forces, a single steel cylinder and coil is not the best geometry. One suggestion is to use a steel cylinder in a steel cup with a coil in between. These designs are much more efficient and there are a lot of...
  20. MagMike

    Surface treatment on steel for NiCuNi magnet bonding

    Ed is correct. Epoxies generally work well with roughened surfaces. In my experience, acrylics work well with smooth surfaces. There are exceptions to both.

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