08:20 Jul-24-2009 aldo Engineering Italy, Joined Jan 2009 39
type of TAM PANEL
The last week my plane has received the first audit NADCAP on PT and RX...The results have been the followings:
1) 3 major on PT
2) 0 major on RX
One major has been on choose tam panel during PT process. The piece was a welding tube and it have all machine surface. The tam PANEL choose has been a grit blasted but the auditor said the correct choose was the tam PANEL polish because your surface was representative of the machine area on piece .
I want your opinion because i do not remeber if there are requirement o sprecific on choose tam PANEL to be processed.
Tanks and best regards
Its been a while since I was involved in this process, but when I was the TAM panel we used was made by Sherwin. One half was blasted and the other half was a smooth polish finish with 5 star cracks on it.
It is a little hard to give you proper advice without seeing your setup and not knowing which aircraft you are working on, but we do have to remember that in NDT, we always compare a known with and unkwown. The known is our calibration piece and the unknown, the part we will be inspecting. So it stands to reason to have both in similar finish, material, heat tretment, etc....
Now as for your requirement, it depends on the code that you are working to. In your situation, the aircraft manufacturer would normally establish the requirement in their codes and specifications and I say normally, because I know that it is the way with Boeing and Airbus. But than again, I don't know which aircraft you are refering to.
mostly Tam panels have two types of sufaces one grit blased which is used to check washbility in Penetrant System, and other is very fine finished surface having star like known defects in 3 or 5 Qty.
defects in welding of tube is depends upon type of welding, thickness of tube, and material,
mostly in tube welding with automated system (Manual welding is hard to control on tube thickness) lack of side wall fusion is common defect, that require high sensitivity in PT so i think u must need a finished surface TAM PANEL
but its better to contact with ur company`s authorised LEVEL III, and ur Codes & specific requirment of PART
Congratulations on your excellent results for your initial Nadcap audit. The PT audit is a particularly difficult one. If you look at the 'Top 25 Findings' for the PT checklist (under public documents in eauditnet) you will see that the tam panel (5.9.1) has by far the highest number of findings against it. You will have to read the finding very carefully and if you have any queries discuss them with the staff engineer before putting any corrective actions forward. I would also advise you to read the Nadcap corrective action procedures very carefully before submitting your corrective actions as it is very frustrating having them returned instantly with the comment 're address the root cause'.
As to your question regarding the tam panel you will have to check the prime specifications as well as the relevent ASTM and AMS Standards. I suspect that the argument will be that a wash that clear background from a grit blasted panel may overwash a smooth component.
I hope this is of some assistance.
Great job on the preparation of the Nadcap pre-audit.As far as all the specification is concerned, there's no specific requirements from primes that indicate what type of TAm panel to be chosen.I am in the aerospace manufacturing inductry and brought up this issue to the primes and was given option to choose myself.Unless specification defined the type of TAm to be used.You may refer to the instruction manual on the TAm panel and refer to ASNT website for more information.
The main requirement to remember is the "TAM" panel is an inspection and acceptance test instrument and it must be calibrated, no different than a micrometer or torque wrench. If you follow the history of the "TAM" panel to its roots you will find a drawing that defines the "TAM" panel. It will give specific dimensions of the star indications, smallest on the bottom and largest on the top, with appropriate tolerances of acceptability. These indications need to be monitored to assure they haven't grown over time presenting a false reading of a Liquid Penetrant system inspection process capability to properly function.
I've read your answer and would like some clarification. You state: "It will give specific dimensions of the star indications, smallest on the bottom and largest on the top, with appropriate tolerances of acceptability. These indications need to be monitored to assure they haven't grown over time presenting a false reading of a Liquid Penetrant system inspection process capability to properly function."
I agree with you as to the specific dimension of artificial defects (stars), but how can these defects grow over time? Your TAM panel shouldn't be submitted to any stress whatsoever. So there is no reason for the indications to grow. On the contrary, if at all, those indications should shrink over time, due to improper cleaning and dried up penetrant following repeated use.
The TAM panel indications may only have to grow a few thousandth of an inch or few millimeter of a meter. This could be caused by the heating and cooling found on the processing line of a water washable penetrant line. Or it could be caused by the vibrations in an ultrasonic cleaner used to clean the TAM Panel. It may be from dropping the panel on the floor. Rough handling of the TAM panel by liquid penetrant line inspection people. The cause of the indication growth may not even be identified. But, the bottom line is, which is cheaper, easier, less embarrassing, and most of all, less damaging to a businesses credibility. Checking the TAM panel and not finding any growth or shrinkage, catching it during a calibration and replacing it. Or, NOT checking it and calling all of your customers and explaining that you have found or an audit team found an inspection process out of control. After that comes the really hard part. Who is going to address the problem financially?
Although I agree that changes resulting of poor handling can happen on a TAM panel, I don't think that the growth of indications would be the results of puting it through the PT process line, specially when the maximum water temperature is 125 degree F. Now changes resulting from the ultrasonic cleaner and mishandling is more plausible.
And I certainly agree with your bottom line. Looking foolish during an audit is not fun, yet many people do not understand the extend of their action and are still going through life like nothing is happening. This is why I believe that whoever is doing the hiring should be cautious in their selection and understand that they have to pay a certain amount of money to obtain quality.
tanks all for yours replay and excuse me for late my replay.... after one call conference with my 3 level primere together 3 level on side, we have decided not to follow the opinion of NADCAP auditor because there are not requirement in codes or specifications on ours supplier....but i have one question:
is necessary to have the same TAM panel working and master with the same surface for example both polish o grit blasted o is possible to have the working ad the master with difference surface for example great blaste for the working and polish for the master and back?
tanks and best regards
I don't understand why you would have a "Master TAM Panel" and "Working TAM Panel". From what I remember, each of them comes with its specific defect size and the size of those defects is confirmed by the Certificate of Compliance that comes with it.
When you do the checks for your PT line, you process the TAM panel and compare your finding with what was given on the Certificate of Compliance. I therefore don't see the use of having a "Master" and "Working" TAM Panel. At worst, if you want you may wish to have a spare TAM Panel in case something goes wrong with the one you are using or if you get different results and wish to confirm your results.
Now, if you have more than one panel, I think they should be the same. Specially if you will compare one with the other. Remember, NDT is comparing a known with and unknown. Therefore all must be the same. Like we say in english, you can't compare apple with oranges.
A couple of points,
I am surprised to see that your prime and responsible Level III advise against following the NADCAP auditors findings, this indicates that they have not understood the NADCAP process. The NADCAP checklist is a minimum requirement with any prime specific points being in addition to the checklist. You must therfore comply or you will not be accredited.
Regarding the TAM Panel, It is normal to take a photograph of the new panel processed with new, unused materials (Penetrant, remover and developer). This Photograph is then compared with the panel during use to spot any deterioration in the process or the panel. As per Para 5.9 Nadcap Audit Criteria AC7114-1.
Again congratulations on your Nadcap audit result. 3 Non-Conformances is not at all bad for a first audit.
Regarding the TAM panel.
The star detection is a method of checking that the sensitivity of the entire system is consistent. It is specific to one identified TAM panel, and your reference photographs should be made with your system and your chemicals on that specific TAM panel. If things change in your process, then the detectability of the stars will change.
There is a requirement for regular checks on apparent defect size to ensure that the TAM panel itself does not change.
I suspect that the non-conformance was raised because you used a TAM panel with a rough surface as your washability reference rather than a polished TAM panel.
I suggest that if you have polished and smooth samples in your normal production that you process one TAM panel with either a rough or a polished surface and one other TAM panel with a smooth or a rough surface (opposite of the first one), BUT you do not evaluate the stars on the second panel. It will then only be used as a washability reference. Alternative would be to process TAM panel plus a separate washability check panel with the opposite finish to the TAM panel in use.
Sucess with your submissions.