Pan head screws vs flat head screws

Discussion in 'General Electronics Chat' started by alphacat, Sep 8, 2009.

  1. alphacat

    Thread Starter Active Member

    Jun 6, 2009
    186
    0
    Hey,

    I wanted please to ask you guys a question.
    Our product consists of three metallic pins - Live, Neutral and Earth.
    These 3 pins are screwed into our plastic enclosure.
    They can carry up to 16Arms which is drawn from the AC mains.

    Will pan head screws handle such current better since there's more space for the electrons to flow through?
    Or there's no difference between pan and flat head screws?

    Thanks.
     
  2. rspuzio

    Active Member

    Jan 19, 2009
    77
    0
    The shape of the screw heads should not make much of
    a difference as far as the electrical properties go. What is
    important is that the pins and wires be thick enough for the
    amount of current anticipated and that the surfaces in electrical
    contact fit together well and be clean.
     
    Last edited: Sep 8, 2009
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,676
    899
    Binder or pan head are most often used. Binder/binding has an even bigger head. Can you post a drawing of how your attachment works.

    If the metal being connected is very thin relative to the height of the flat head, you will have a weak joint. What included angle of flat head are you using?

    John
     
  4. alphacat

    Thread Starter Active Member

    Jun 6, 2009
    186
    0
    Hey,

    Thanks alot for the help.

    Here's how it all goes:


    [​IMG]

    So is it indeed electrically important to have the heads as big as possible for the current to flow easily ?
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    It appears that the screw carries no current, nor is it being used to connect a ring connector to a terminal. Thus, the main consideration is mechanical.

    Flat head screws are commonly available in 82°, 90° (usually metric), and 100° (common for aircraft) included angles. Rarely, you might find 110° included angle. The 100° will give the most binding surface for thin sheet metal, hence its use in aircraft. Presumably, you are using something like a #8 or #10 screw.

    You can find tables that show the minimum thickness needed for each screw size and head angle to prevent needing to countersink the mating or back surface. In your case, it is the plastic. I would avoid doing that, as it leads to a weaker joint.

    Overall though, I don't see it an an electrical problem. Some main attachments are simply held in place with a barb and actually float a little in the plastic enclosure.

    John
     
  6. alphacat

    Thread Starter Active Member

    Jun 6, 2009
    186
    0
    Hey John,
    Thank you so much for this great info :)

    I tried finding such tables but didnt encounter any.
    Could you please direct me to such?
     
  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,676
    899
    I have to run right now. Check McMacter-Carr (mcmaster.com). I may be there in an "about xxx" section.

    I will check other sources when I get back.

    John

    Edit: Here's a link: http://www.mcmaster.com/#about-machine-screws/=3ji4yt
    Search term: about flat-head machine screws. The metric data are probably for 90° included angle.
     
    Last edited: Sep 8, 2009
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