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Help in designing electromagnets

  1. Mar 30, 2017 #1
    Hi all,
    First post, be gentle...

    I'm trying to build a system based on the MIT Actuated Workbench.
    They used electromagnets with the following spec:
    1.9cm (0.75”) diameter x 3.8cm (1.5”) length, wound with 32-gauge copper wire with a total length resistance of 120-122 ohms, with no metal housings so to not focus the magnetic field.
    They used 27 DC volts and draws about 250mA.

    From what I read, it seamed to be an almost arbitrary choice though, so I was hoping to optimist the design to create more forces. I was also hoping to use a more standard 24V power supply (not sure why they used 27...)

    I'm not sure where to start this process and I was hoping to get some advice.

    I thought maybe some trial and error through a simulation tool could work, but tell me what you think (also for that, so far I saw recommendations for FEMM, MaxFEM, Vizimag, Elmer and OpenFOEM, so I could also use a recommendation for which one to use)

  2. jcsd
  3. Mar 30, 2017 #2

    jim hardy

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    Science Advisor
    Gold Member

    So is the question "how does one calculate strength of an electromagnet? " ? Any search engine should respond to that question.
    The basic approach is amp-turns per unit length X permeability.
    With 32 gage wire it's a sure bet they used copious turns and meager amps to get the amp-turn product they wanted.
    You already know the amps, around ¼ .
    To estimate # turns figure length of #32 to make 120 ohms. How many times will that wrap around a ¾ inch core?

    The video you posted is long on applications but short on mechanical details.
    They gave no clue how they detect position of a puck over the array of electromagnets.

    It's hard to figure out what you are asking.
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