1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Solenoid, armature length

Discussion in 'Mathematics and Physics' started by ccurtis, Nov 9, 2017.

  1. ccurtis

    ccurtis Active Member

    Joined:
    Dec 22, 2008
    Messages:
    949
    Likes:
    52
    Location:
    NJ, USA
    It is well established that the axial force on a solenoid armature is an inverse, exponential function of the distance that the armature protrudes from the coil. This is because of the air gap that exists and changes with that distance.

    So, I'm wondering if I make the armature longer than the coil length, protruding out both ends of the coil, but offset from center, does that helps to increase the initial force on the armature since the armature always fills the hole in the coil (no air gap) and the force seeks to center the armature?
     
  2. shortbus=

    shortbus= Well-Known Member

    Joined:
    Mar 23, 2008
    Messages:
    1,227
    Likes:
    77
    Location:
    youngstown, oh
    Would an armature like that even move? An armature that is all ready in the coil would only become magnetized wouldn't it?
     
    • Agree Agree x 1
  3. alec_t

    alec_t Well-Known Member Most Helpful Member

    Joined:
    Jul 10, 2011
    Messages:
    9,289
    Likes:
    1,222
    Location:
    Cardiff, Wales
    I think the armature will tend to centralise itself in the energised coil, so that the push-pull effects of the protruding parts will cancel each other out.
     
    • Agree Agree x 1
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. shortbus=

    shortbus= Well-Known Member

    Joined:
    Mar 23, 2008
    Messages:
    1,227
    Likes:
    77
    Location:
    youngstown, oh

    I may have misunderstood the description, but I took it as the armature was already centralized in the coil, with equal lengths extending out of the coil.
     
  6. alec_t

    alec_t Well-Known Member Most Helpful Member

    Joined:
    Jul 10, 2011
    Messages:
    9,289
    Likes:
    1,222
    Location:
    Cardiff, Wales
    The OP says "offset from center".
     
  7. shortbus=

    shortbus= Well-Known Member

    Joined:
    Mar 23, 2008
    Messages:
    1,227
    Likes:
    77
    Location:
    youngstown, oh
    But in that same sentence he says, "So, I'm wondering if I make the armature longer than the coil length, protruding out both ends of the coil"
     
  8. alec_t

    alec_t Well-Known Member Most Helpful Member

    Joined:
    Jul 10, 2011
    Messages:
    9,289
    Likes:
    1,222
    Location:
    Cardiff, Wales
    I read the OP to mean it doesn't necessarily protrude by equal amounts at the two ends.
     

Share This Page