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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.  

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,

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 

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.  

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.

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 

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.  

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
------------------------------

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
------------------------------

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------

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

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------

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?

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

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------

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?

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

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------

Original Message:
Sent: 11/14/2023 9:09:00 AM
From: Colin Fletcher
Subject: RE: Cold work

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

Original Message:
Sent: 11-14-2023 08:29
From: Eli Yudkevich
Subject: Cold work

Original Message:
Sent: 11/14/2023 7:56:00 AM
From: Colin Fletcher
Subject: RE: Cold work

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

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------

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
------------------------------

Original Message:
Sent: 11-14-2023 22:48
From: Eli Yudkevich
Subject: Cold work

Original Message:
Sent: 11/14/2023 9:09:00 AM
From: Colin Fletcher
Subject: RE: Cold work

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

Original Message:
Sent: 11-14-2023 08:29
From: Eli Yudkevich
Subject: Cold work

Original Message:
Sent: 11/14/2023 7:56:00 AM
From: Colin Fletcher
Subject: RE: Cold work

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

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------

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
------------------------------

Original Message:
Sent: 11-12-2023 23:47
From: Eli Yudkevich
Subject: Cold work

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
------------------------------