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Cold work

  • 1.  Cold work

    Posted 11-12-2023 23:48

    Hello, 

    copes with cracks during cold working in holes. The 5/16" drilled diameter holes are treated on 2 bonded plates on  6al-4v panel.   . 

    Any idea how to avoid it will be appreciated.  



    ------------------------------
    Eli Yudkevich
    consultant engineer
    self employ
    kfar saba
    972 523663911
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  • 2.  RE: Cold work

    Posted 11-13-2023 08:39

    Hello,

    Could you offer more details of the application and the prior preporation of the panel that failed.  I assume the material in question is Ti6AlV4.



    ------------------------------
    Michael Zielinski
    Lehigh Univ
    Easton PA
    90846973332218
    ------------------------------

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  • 3.  RE: Cold work

    Posted 11-13-2023 09:47

    Eli,

    Borrowing from my past life as an aviation technician/machinist: Reaming of holes after drilling is a common step for any precision fit.  This is two-fold for dimensional and roundness tolerance.   Cold-working an oval or triangular hole would certainly increase stresses beyond those anticipated.  

    Cold worked inserts to repair oversized holes in aircraft panels exist and you may find some knowledge in their installation procedure.  

    Regards,
    Benjamin Carter P.E.
    Mechanical Integrity Program Manager, API 510 & 570
    Grifols Therapeutics LLC  |  www.grifols.com 
    Cell: 919.746.6805 



    ------------------------------
    Benjamin Carter
    Mechanical Integrity Program Manager
    Grifols Therapeutics
    Apex NC
    ------------------------------

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  • 4.  RE: Cold work

    Posted 11-14-2023 08:30

    I would like to add to Benjamin's response.  For precision machining (and if you are reaming holes, this is considered precision machining), the standard practice is to drill the hole (maximum material removal), then bore the hole (both for a precise location, and to true the hole), then to ream for final size.  Note: the reamer will "follow" the existing hole.  A drilled hole is neither round nor on location, and a reamer is only meant to remove a small amount of material.  If the hole is severely out of round, then the subsiquent reaming operation might cause some cold work where the reamer is removing more material around the existing drilled hole.



    ------------------------------
    Michael Zielinski
    Lehigh Univ
    Easton PA
    90846973332218
    ------------------------------

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  • 5.  RE: Cold work

    Posted 11-14-2023 08:39

    This is exactly what we do... and still we see some crakes.

     

    BR  

     

        Eli  Yudkevich

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      Aerospace manufacturing

               specialist

     

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  • 6.  RE: Cold work

    Posted 11-14-2023 07:56
    Edited by Colin Fletcher 11-14-2023 07:57

    Eli,

    I concur with Michael that more details would be helpful. Are the cracks radial, or is the entire plate/panel failing? Is the cold working performed sleeved or sleeveless? Along which axis is the cold working performed (e.g., L, LT, ST)? Is the 6Al-4V panel in the annealed condition?



    ------------------------------
    Colin Fletcher, PE
    Sr. Advanced Materials Engineer
    Honeywell Aerospace
    &
    Metallurgical Consultant
    Longleaf Materials Research
    Cary NC
    ------------------------------

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  • 7.  RE: Cold work

    Posted 11-14-2023 08:29

    Hi Colin,

    Herein some answers for your questions :

    The cold working performed sleeved, the 6AL-4V is annealed ,CW performed in L axis. When we doing ultrasonic, we see bonding failure .

     BR

     

     

        Eli  Yudkevich

              Consultant 

      Aerospace manufacturing

               specialist

     

    Mobile: 972 52 3663911

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  • 8.  RE: Cold work

    Posted 11-14-2023 09:09

    Thanks. Just to confirm my understanding:

    • There are two 6Al-4V panels
    • The panels have been adhesively bonded
    • Holes are drilled, cold worked, and reamed
    • NDT reveals that adhesive has debonded (in the shaded area), which is the primary concern

    Is this the case?



    ------------------------------
    Colin Fletcher, PE
    Sr. Advanced Materials Engineer
    Honeywell Aerospace
    &
    Metallurgical Consultant
    Longleaf Materials Research
    Cary NC
    ------------------------------

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  • 9.  RE: Cold work

    Posted 11-14-2023 09:54

    Exactly ...

     

     

        Eli  Yudkevich

              Consultant 

      Aerospace manufacturing

               specialist

     

    Mobile: 972 52 3663911

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  • 10.  RE: Cold work

    Posted 11-14-2023 22:48

    Exactly !

    Aby help will be appreciated .

     

    Thank you

     

        Eli  Yudkevich

              Consultant 

      Aerospace manufacturing

               specialist

     

    Mobile: 972 52 3663911

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  • 11.  RE: Cold work

    Posted 11-15-2023 07:46
    Edited by Colin Fletcher 11-15-2023 07:46

    Assuming the process has been successfully performed with this adhesive in the past, I would take a look at surface preparation next. If the surfaces were not completely clean or otherwise not properly prepared for bonding, a debond like this could occur during cold working. If this adhesive has not been used before, then a more flexible adhesive may be better suited.



    ------------------------------
    Colin Fletcher, PE
    Sr. Advanced Materials Engineer
    Honeywell Aerospace
    &
    Metallurgical Consultant
    Longleaf Materials Research
    Cary NC
    ------------------------------

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  • 12.  RE: Cold work

    Posted 11-15-2023 10:53

    Thank you !

     

        Eli  Yudkevich

              Consultant 

      Aerospace manufacturing

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    Mobile: 972 52 3663911

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  • 13.  RE: Cold work

    Posted 11-14-2023 08:52
      |   view attached

    See attached a picture showing the deboned areas.

     

     

        Eli  Yudkevich

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