Safety-wire qualities

Discussion in 'General Experimental Aviation Questions' started by erkki67, May 26, 2019.

Help Support HomeBuiltAirplanes Forum by donating:

  1. May 26, 2019 #1

    erkki67

    erkki67

    erkki67

    Well-Known Member

    Joined:
    Feb 18, 2010
    Messages:
    1,653
    Likes Received:
    179
    Location:
    Romont / Fribourg / Switzerland
    Hello there

    Safety-wire do have to meet the MIL ... standards.

    Can it be that the tensile strenght differs between two products?

    I've a more shiny wir that breaks in my opinion quiet quick, and second wire that is more matt in color that I can twist further before it comes appart!

    Do you have any thoughts how to search for the more elastic ones?

    Erkki
     
  2. May 26, 2019 #2

    TFF

    TFF

    TFF

    Well-Known Member

    Joined:
    Apr 28, 2010
    Messages:
    11,721
    Likes Received:
    3,320
    Location:
    Memphis, TN
    It work hardens as you twist it on purpose. Don’t put too many twists in it. There is of course mill spec. I twist about 12-15 turns an inch. The super tight twisted 20 plus usually are already overworked. I have noticed twisting wire is almost like a signature. If you know the group you are working with, you can pick out each ones wire job. And with that some can twist it until the cows come home and never break it while some break it two three times before they get one to stay.
     
  3. May 27, 2019 #3

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,974
    Likes Received:
    1,921
    Location:
    North Carolina
    Suck it and see. safety wire should start off annealed. It could be that they are different alloys.
     
  4. May 27, 2019 #4

    Angusnofangus

    Angusnofangus

    Angusnofangus

    Well-Known Member

    Joined:
    Sep 29, 2015
    Messages:
    329
    Likes Received:
    143
    Location:
    Victoria, Canada
    All the safety wire I have ever seen is stainless steel, different thicknesses, I think that .020 is the thinnest, the thickest I've seen is .063. There IS copper witness wire, but that is a different function.
     
  5. May 27, 2019 #5

    cvairwerks

    cvairwerks

    cvairwerks

    Well-Known Member

    Joined:
    May 12, 2010
    Messages:
    174
    Likes Received:
    65
    Location:
    North Texas
    Be aware that there are 6 different material codes for safety wire. Monel, Inconel, CRES and Carbon steel all have very similar appearances, so check the can or roll label to verify what you have. The spec is MS20995/NASM20995.

    Wire is available in diameters of .015" to .091" depending on material. Copper is used both as witness wire and in electronic installations where good conductivity is required for grounding or EMI shielding is needed to be maintained thru the fastener.
     
    bmcj likes this.
  6. May 27, 2019 #6

    erkki67

    erkki67

    erkki67

    Well-Known Member

    Joined:
    Feb 18, 2010
    Messages:
    1,653
    Likes Received:
    179
    Location:
    Romont / Fribourg / Switzerland
    For sure it’s a stainless steel wire we are using, our purchase engineer told me that it fulfills the MIL specs, but the new one they bought breaks very fast, and this is annoying, especially in very tight areas.

    So Id like to have a look for a .032 thick wire, our standard size, that is some kind of more elastic but still fulfilling the MIL specs.
     
  7. May 27, 2019 #7

    cvairwerks

    cvairwerks

    cvairwerks

    Well-Known Member

    Joined:
    May 12, 2010
    Messages:
    174
    Likes Received:
    65
    Location:
    North Texas
    Erkki: Watch the twist rate and how much tension you are applying as you twist. There is not a tensile strength listed for safety wire, but knowing the alloy from the specification, you can derive it. It might be worth trying MS20995NC32, but it's 3x the price as regular wire.
     

Share This Page



arrow_white