Detecting cracks in aluminum...
Dragon
magnaflux steel or cast but I don't believe this method will work on
aluminum. Is there a chemical or another process for checking aluminum?
Thanks in advance for your replies!
PLAlbrecht
Zyglo. Spotcheck is done in visible light. Zyglo requires an ultraviolet light
source to see the fluorescent dye that goes into whatver cracks may be lurking.
Pete
Wolfgang Habicher
A method that will detect cracks in ALL non magnetic materials is called
Dye Penetrant Examination, or PT examination for short.
Look in the yellow pages for an outfit that does Non-Destructive
Examination of all types, they can help you, or at least direct you to
someone who can. The equipment required is inexpensive and most
portable.
In essence it consists of these steps:
1) Clean the object (area) to be examined and make sure it is dry.
2) Spray on the dye penetrant. This is a red dye (suspension, solution?)
in a very thin oil, and soaks into the crack.
3) After a soaking period, say 15 minutes or so, wipe off all traces of
the penetrant.
4) Spray on the developer, which is a very fine, dry, powder. The red
dye that soaked into the crack will be drawn out by the powdery
developer, showing the location of the crack, clearly.
A couple of caveats: Do NOT sand blast or grind the area to be examined,
as this tends to hammer or smear the crack edges thus hiding the crack.
If all fails you can talk to some aircraft maintenance mechanics, they
use this process extensively for airframe crack detection.
I also believe you can buy a kit that contains the necessary spray
containers to do the job. All you'd have to do is appropriate your
wife's or girlfriend's underwear for the cleaning task. Cotton
Tee-shirts work also very well.
Good luck, Wolfgang
John Robertson
wrote:
You might try the old Hot Rodder trick. I've wiped diesel fuel on old
cast iron blocks and heads, wipe off as much as you can with a shop
rag, then put baby powder on it ( the metal not the shop rag!). The
crack shows up wet because of the fuel that was not removed. I never
tried it on AL but it might work>
John Robertson
Katy (Houston), TEXAS!!
---------------------
Visit the Steam & Stuff Page
http://www.intergate.com/~john/page11.html
Jesse Brennan
>
>I have an aluminum engine that I need to check for cracks. I know you can
>magnaflux steel or cast but I don't believe this method will work on
>aluminum. Is there a chemical or another process for checking aluminum?
>Thanks in advance for your replies!
>
the part, spray on a thin liquid die from a spray can, whipe the surface dry and
spray on a white "developer". cracks show up as die marked line. you should find
this at a local machine tool supply house or maybe an auto parts store.
The mail order tool houses ( MSC or wholesale tool etc). This is the most out
of the box way.
Jesse
Rnkknr
there is NO substitute for pressure testing.You didn't mention if it was a
block or head or both you need tested but basically you block off all the water
ports and pressurize the water jacket with 40 psi. Spray the surface with a
dilute soap and water soloution. It will be very obvious where the cracks are.
I have had come backs that penetrant dye missed such as a crack running with
the counterbore for a valve seat in a mitsubishi cylinder head. Not a problem
to fix but undetectable by any dye test. Pressure test will catch it every
time.
Rudy
Quality Machine and Hydraulics
Member AERA
Specializing in the repair of cracked cylinder heads, both cast iron and
aluminum.
Phil
production environment, you can find cracks fairly quickly this way. However, I
never found a crack that I couldn't have found without the zyglo, if I had looked
closely. If I just had one casting to check. I'd just look it over very closely.
If it's cracked, you'll see it. It just takes a little longer than with zyglo,
where as soon as you put a black light on it, the crack shows up as a line of
green.
Phil
Phil
Phil