Use of markers on aeronautic parts 1

[roberto1brazil]

Hello everybody.
Please, I need some advices about the use of markers on aeronautic parts. In the aeronautic industries the use of markers is restrict to some ones because of contamination that some products can cause on parts. At my company we make use of a marker with red wax. It is easier to be removed from surfaces but at same time if the original mark is erased when the part is cleaned, we have difficulty to localize the problem again if , for instance, there was a crack on the surface. Making use of a permanent ink marker (on machined or polished surfaces except porous surface) it would be more difficult to lose the original mark. Question - Is there some inconvenience in using such kind of marker on the parts?
Thanks for any information about this issue
Roberto

 

[Sparweb]

Tagging or bagging the part will be helpful to identify it as a part with flaws, with no other marks on the part itself.
Locating the flaw again after the part has been cleaned (removing all ink or wax marks) could be done with photographs or a paper template (trace the outline of the part, then draw the location of the flaw).


STF

 

[WKTaylor]

Roberto1brazil...

Rule-of-thumb about marking on aircraft parts: DO NO HARM.

DO NOT USE carbon lead pencils on bare metal. EVER. The carbon is hard/impossible to remove and will react with most metals in a decidedly nasty way!

OK to use permanent ink felt-tip pens [Sharpies, etc], any color, EXCEPT BLACK! (quiz: why not black?)

There are also colored paint-pens that are generally OK, assuming solvent based thinner will remove it.

At one time a special pencil [silver marking 'lead'?] was allowed for marking bare or painted metal... however these are geneally NA.

For GOD SAKES, NEVER mark on metal with a scribe [or pointed-tip metal punch], unless You mean to cut along that line or drill thru the punch-mark.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true.
o For those who believe, no proof is required; for those who cannot believe, no proof is possible.
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
o Learn the rules like a pro, so you can break them like an artist. [Picasso]

 

[GregLocock]

I bet navy blue is almost as bad as black, and to the male eye, indistinguishable.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[tbuelna]

roberto1brazil-

Take a look at MIL-STD-792 section 5.11. You can also refer to AS478 which provides extensive information on marking methods for aerospace components.

Here's a good tip for you. In the future, if you are looking for a specification/standard for a particular process (such as temporary marking of special purpose components) start by reading the list of referenced documents in a related process standard. For example, you noted the temporary marking was used to indicate a surface defect. So the first thing I did was pull out a copy of ASTM E1417 (penetrant inspection) and read the list of referenced documents, which included MIL-STD-792 Marking Requirements for Special Purpose Components.

Hope that helps.
Terry

 

[roberto1brazil]

Hello.
Thanks all of you for the tips and advices. I will check all the information involved.
Regards

Roberto

 

[WKTaylor]

roberto1brazil...

Greglocock made (2) very important points in one statement.

#1 Be cautious about Navy blue ink... especially if it is darkened with black dyes. However, a typical 'Sharpie blue' felt-tip [I have one spinning on my desk at this moment] is unmistakeably pure blue dye. IF IN DOUBT call the manufacturer and verify that the ink/dye do not contain carbon [lamp-black, refined carbon powder, etc].

#2 I, and ~10% of all males [much less than 1% all females], have some degree of color blindness. A story that 'Kelly Johnson' related was an experience at the Skunkworks in early 1950s: they tried color-coding some critical parts only to discover the 'experiment went hay-wire' since they had a higher percentage of color blind mechanics than the population. Positive written ID and B/W pictographs, clear drawings and production illustrations, etc were required for these people [good mechanics, just color-vision deficient]. Also NEVER forget that color/vision changes as people age. Same for hearing!

NOTE. There are special inks for heat treatment and permanent part markings [ink-stamp, etc], such as dark greens and reds, per MIL-STD-130 and AS478. Tubuelna Mentioned MIL-STD-792... which I was unaware of... as another good reference.

NOTE. For temporary marking, [especially, when cutting/drilling/machining IE: laying-out a pattern], machinist dyes (blue, red, green) etc are useful [on cleaned metal surfaces], using sharpened plastic or wood pens or deliberate scribe or punch marking [carefully].

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true.
o For those who believe, no proof is required; for those who cannot believe, no proof is possible.
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
o Learn the rules like a pro, so you can break them like an artist. [Picasso]

 

[dgapilot]

Depending on the product, within Chapter 20 of the maintenance Manual there should be a consumable materials list. Any markers that can be used should be listed here.