Electromagnet Force

Discussion in 'The Projects Forum' started by LOGON, Mar 20, 2013.

  1. LOGON

    Thread Starter New Member

    Mar 18, 2013
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    Hello everyone,

    I have a project in hands with the objective to create a electromagnetic force capable of moving and doing a pression on a membrane (more a less 200N) mechanically coupled with a iron rod. This pression is done very quickly with cycles of 1s or 2s...possible controlled with PWM.

    I cant use a solenoid because its take a long time to move, that is, the greater the strength more longer it will take.

    It is possible to construct or buy a electromagnet with that specific characteristics? The iron rod will function like a core of the electromagnet and moves both sides...

    Any help i will thank you...

    Cheers
     
  2. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    What you described is a solenoid. A coil of wire around a hollow tube, that will fit over your iron rod.
     
  3. LOGON

    Thread Starter New Member

    Mar 18, 2013
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    Yes the operating principle is the same...

    I found a new possibility to do this by using DC linears actuators, but with this quickly cicles they will not last long.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    A loudspeaker comes to mind. A large, high-power bass speaker would have a large permanent magnet with a heavy gauge wound coil on a tube connected to the speaker cone; the coil moves the cone instead of the magnet.

    It sounds like your application is somewhat similar, in that you need rapid response with a good deal of force. 200N is roughly 45lbs (pounds) of force. I don't know offhand how one would figure out how much power you'd need to generate that much force; however I'll guess around 1/4 horsepower or about 186 Watts.
     
  5. John P

    AAC Fanatic!

    Oct 14, 2008
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    I don't see how anyone can offer suggestions of how much power is needed, because the question was asked in the glorious tradition of this forum, guarding the information needed to answer it as the most precious secret.

    How much mass?
    How much acceleration?
    Any friction?
    What stroke length?
    Any stored energy (springs, gravity, etc)?
     
  6. Duane P Wetick

    Active Member

    Apr 23, 2009
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    There is not a simple answer to your question. A flat face type of magnet as is used in magnetic clutches and brakes comes to mind. The Force equation for this type of a magnet is Force = (B) sq. x (r) sq. /11.45 = lbs. where B is the magnetic flux (lines / sq. in.), r = center pole radius. Companies who manufacture these types of electromagnets consider this data proprietary and do not give it out.

    Cheers, DPW [ Everything has limitations...and I hate limitations.]
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Or it could be done mechanically, with an crank on a motor and a connecting rod.
     
  8. LOGON

    Thread Starter New Member

    Mar 18, 2013
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    Thank you by all replys. :)

    How can i post the schematic in a pdf?

    I have already contact a some electromagnets manufactures and they reply to me that cant produce nothing like this...

    I think i will try with the linear actuators but with longer cycles...
     
  9. LOGON

    Thread Starter New Member

    Mar 18, 2013
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  10. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    And it is a solenoid. Solenoids are capable of two way power if you have the right type. A coil of wire at each end of the solenoid, separate from each other. the actuator rod would need to be non-magnetic, with a magnetic "piston" on its end. The piston in rest position would be in between the coils, and when a coil is activated, the piston would move toward that coil.

    It would help us to help you if you told us what you are trying to do.

    To upload attachments, click on the "go advanced" button, on the reply area.
     
  11. LOGON

    Thread Starter New Member

    Mar 18, 2013
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    It is something like the schematic, the objective is moving two plungers (or membranes).

    P=F/A if it is a membrane with d=0,2m P=6451,6 Pa = 0,06 bar

    The difficulty here is doing a very quickly push and pull cycle (2s or 3s), solenoids take too long to do this...
     
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  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    That doesn't help much. Don't understand why you say solenoids don't move fast enough. They can move in miliseconds. But one coil with an iron shaft won't move lime you want.
     
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