Causes of Disbond Defects in Composites Manufacturing Process

nismoynr

Starting to get Involved
#1
Hi all,
i have a problem which make me in trouble.:( is there anybody know what is the cause of disbond defect occur in composite manufacturing process? right now we still said that the poor handling is the cause of the disbond. another question is, how we going to do the root cause analysis for defect such as disbond, FOD, indication, etc? hope you guys can help me..
 
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Jen Kirley

Quality and Auditing Expert
Staff member
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#2
Welcome to the cove!

You haven't said exactly what materials you are using. Disbonding in composites, its inspection and its repair were listed in about 11,900 Google "hits" when I did a search using key words "cause of disbonding composites."

Diab Group (I am not affiliated) put out a paper titled Causes, Mechanisms and Preventive actions to Avoid Blistering that lists causes such as air entrapment (33%), uncured CBA (26%), inhibition (22%), low Tg. CBA/Resin (11%), and other causes (8%). You may need to get a book for this one. :(
 
2

20110525R

#3
Hi all,
i have a problem which make me in trouble.:( is there anybody know what is the cause of disbond defect occur in composite manufacturing process? right now we still said that the poor handling is the cause of the disbond. another question is, how we going to do the root cause analysis for defect such as disbond, FOD, indication, etc? hope you guys can help me..
It sounds to me like you have a process problem. It may very well be contamination, improper cure, out of date shelf life materials or other. I would suggest you do a validation of your procedures and processes. If you aren't controlling the materials (i.e. Resins, Materials, Shelf Life, Environmental or Handling) then you will find that in a Validation/Verification of the processes. Run through an internal audit with your procedures and see if anything is not being performed per your Process Specs or if there are factors that are influencing the process (mishandling of materials, process errors, etc). I think you will find issues that have an affect on the outcome of the finished product that no one is paying attention to. Overall, I would suspect contamination or materials not being controlled correctly as the culprit.
Mike
 

nismoynr

Starting to get Involved
#4
It sounds to me like you have a process problem. It may very well be contamination, improper cure, out of date shelf life materials or other. I would suggest you do a validation of your procedures and processes. If you aren't controlling the materials (i.e. Resins, Materials, Shelf Life, Environmental or Handling) then you will find that in a Validation/Verification of the processes. Run through an internal audit with your procedures and see if anything is not being performed per your Process Specs or if there are factors that are influencing the process (mishandling of materials, process errors, etc). I think you will find issues that have an affect on the outcome of the finished product that no one is paying attention to. Overall, I would suspect contamination or materials not being controlled correctly as the culprit.
Mike
thanks mike for the explanation.
our material is nomex h/comb core with 6inch thick.
we already perform process audit but still we can't find what is the exact cause of it..
maybe the audit is not thorough enough.
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#5
You might also add incorrect raw material for the composite. Some fibers need to have the correct suface finish - coated, etched, etc. - to ensure proper binding to the resin system. You may also need material in the resin-rich area to stop propogating cracks. That is a compounding question, however.
 
M

MIREGMGR

#6
Is your process audit also a material surface chemistry analysis, to detect variances between your materials' status as of their qualification and their status now?

You can't rule out contamination and material variance if you only audit parameters that you already understand and control. Sometimes you need to determine that something is different even though you don't understand how and why, as the first step in a process of getting to an understanding of how and why.
 
2

20110525R

#7
thanks mike for the explanation.
our material is nomex h/comb core with 6inch thick.
we already perform process audit but still we can't find what is the exact cause of it..
maybe the audit is not thorough enough.
I don't think your audit was thorough enough either. Did you compare your procedures to the Process Specs to make sure your procedures are correct? I think you need a very thorough Validation/Verification of your processes and procedures, not just a cursory review (audit of procedures). In other words, make sure the process works like it's supposed to and you cover the process specs above all. I think you have overlooked or missed something in your audit.
Mike
 

nismoynr

Starting to get Involved
#8
I don't think your audit was thorough enough either. Did you compare your procedures to the Process Specs to make sure your procedures are correct? I think you need a very thorough Validation/Verification of your processes and procedures, not just a cursory review (audit of procedures). In other words, make sure the process works like it's supposed to and you cover the process specs above all. I think you have overlooked or missed something in your audit.
Mike
we'll try to make a process flow map to understand the process and also what is the related spec/procedure for each process.
 
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