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  • Users: opster
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  1. opster

    FEA question

    Hello, I'm designing a magnetic device very similar to a speaker circuit (i.e. a bottom and top plate, a central pole, and a ring magnet). The only exception is that I'm adding an adjustable leakage path on the outside diameter, and inserting a coil in the empty space between the ring magnet...
  2. opster

    Laboratory electromagnet

    I don't think so. I have two 1in diameter by .5inch length NdFeB magnets and they would give around .4T over that gap, but the field is not uniform at all, a lot stronger in the middle and weaker as you head towards the edge (by about 50%). I probably could have designed the circuit to eliminate...
  3. opster

    integrating flux meter question

    I'm in need of a integrating flux meter. Does anyone know of one that is below $1000.00. I've been sampling the voltage at 5000Hz and digitally integrating, but I still I have some drift (1%of reading per second) that has been giving me a headache.
  4. opster

    Electromagnet to actuate a permanent magnet

    I'm currently working on two projects that deal with magnetism, and one of them invlolves pulling a piece of iron .75x.6x.1in from a distance around .3-.5inches. I have been able to generate a force of 2 to 4lbs, with a 1inch cube permanent magnet (NdFeB). The pulling force is varied (1 to 4lb)...
  5. opster

    Laboratory electromagnet

    I'm done! Everything went well. I ended up with 14.5gauge wire rated at 200C. The vendor wasn't going to have 14gauge in for a few weeks, so I settled. For a recap: Structure (frame): "As I mentioned before I have a space restriction that limits the pole center to be 4.5" off the ground. What...
  6. opster

    Laboratory electromagnet

    Mike, Sorry, my fault. I checked my spreadsheet and realized I used 10% oover the gauge diameter (for insulation) and then an additional 15% for random wound so that's how I got 18lbs per coil. Oh well, if the magnet doesn't end up being strong enough I'll get some more wire.
  7. opster

    Laboratory electromagnet

    Mike, I think you meant 18 pounds per coil and roughly 14000 turns per coil, right? Else I'll need to get some more wire. Saul
  8. opster

    Laboratory electromagnet

    For an update, I have nearly finished constructing the electromagnet. The frame is done. As I mentioned before I have a space restriction that limits the pole center to be 4.5" off the ground. What I ended up with was 1.5"x4" cross section steel for the base and two yokes (I think that's the...
  9. opster

    Laboratory electromagnet

    Oh, Actually the trial version I have been using is the 2D version of Magnet. I like it a lot better than the other trial version by Maxwell, but it's still a trial version so I haven't been able to simulate a exact design, only an approximation. Thanks for all the help, I'm going to talk...
  10. opster

    Laboratory electromagnet

    Thank you MJR2, Are you working with something similar to MREs also?
  11. opster

    Laboratory electromagnet

    so with 1.75inch poles and 1.75 inch (diameter frame), I have a coil ID of 1.75in and an OD of 5.5in. The coils can be as long a reasonable. The electromagnet needs to be able to operate for at least 5 min at a time with say 20 min inbetween, pulse operation won't work.
  12. opster

    Laboratory electromagnet

    I've really not been clear, so please excuse me, I'm usually never this bad. What I need is a electrolmagnet capable of nearly saturating a rubber with 29% iron particles. I've seen journal articles where a air gap (nothing inbetween the poles) flux density of 0.45 T was sufficient to get to the...
  13. opster

    Laboratory electromagnet

    Didn't see the last part of your reply. I'm going to have a double lap shear fixture inbetween the poles. The fixture is attached to a high frequecy horizontal tensile tester. The specimen is going to be some soft rubber with iron particles, 30% iron 70% rubber (MRE magnetorheological...
  14. opster

    Laboratory electromagnet

    Thanks MJR2, I'm sorry but I meant 0.6T not 2T. Could I wind the coil by hand? Also I plan on running the electromagnet for 20 min periods with say an hour break. I could calculate the heat transfer and all of that, but in your opinion will the coil I described above be able to handle say...
  15. opster

    Laboratory electromagnet

    I'm very sorry, for calculations above ID =1" OD=8"
  16. opster

    Laboratory electromagnet

    sorry, I meant 0.6T
  17. opster

    Laboratory electromagnet

    I did some calcs for the size of the coil and came up with this: .75"x1" pole face (only have access to trial 2D software) .75" gap on a C-Frame 1"x1" bar stock for C frame 1010 steel 18gauge wire D=.0407" use .0515" for calcs 1" ID coil with 4" OD and height of 2.5" -> No.of turns 2830...
  18. opster

    Laboratory electromagnet

    Actually I thought of some more useful information. Even though the gap between the poles will be around 1", it will ont be entirely air. Instead it will be a rubber filled with about 30% iron particles, so I'm guessing the relative permeability is around 20.
  19. opster

    Laboratory electromagnet

    Hello, I need to make a laboratory electromagnet that can produce an induction of ~1T over a 1"x1" area with an air gap of about 1" . I have a small budget ~$1000. Which is why I think I'll have to make it. Can somebody give me a few pointers on what iron I should use? I know it should be of...
  20. opster

    estimate axial field for disc shaped perm magn

    I need a rough idea of the field strength and gradient as a function of axial distance for a disk shaped perm magnet. I found a formula on the internet (http://www.magnetsales.com/Design/DesignG.htm) that I don't think is right. Shouldn't the formula be corrected for the demagnetizing field (...

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