Identify Metals 2

[KSmith22]

Hello,
I work in Quality Assurance for an Aftermarket Clutch Manufacturer. One of my duties is to test samples against various specifications and approve or deny them based on the results.
One step of the testing requires me to disassemble a clutch cover to see whether the pressure plate is cast iron or ductile steel. The process is to either drill out the rivet or grind off the straps, both of which are time consuming and present availability problems (regarding the drill press). What I am looking for is a non-evasive way to test the plate. Is there a non-hazardous chemical that can be applied to a small section that would react with the metals differently? A hardness test has been suggested, but the availability issue applies.
I would appreciated and comments/suggestions on this idea.
I would appreciate if a brief explanation as to why or why not is included.

Thanks,
K. Smith
Quality Inspector

 

[ElderX]

There are some x-ray diffraction or fluorescence tests that can be applied that are non-destructive.

 

[KSmith22]

The X-Ray diffraction sounds like more than we can do, but the fluorescence test sounds interesting. Where might I find more information on this procedure?

Kevin Smith
Quality Inspector

 

[ElderX]

http://www.tn-technologies.com

 

[pipewelder1999]

If you rub the machined surface of gray cast iron with a piece of paper, the free graphite will be visible on the paper. This will not be true with steel. If you are not referring to gray cast iron, then this test will not apply.

Also be aware of dust/shop dirt and oil.

Gerald Austin
Iuka, Mississippi

http://www.weldinginspectionsvcs.com

 

[hammaad]

1-find a match standard (a ket of peicecs in a box). then you can rub the surface of material and try to find by matching it with match standard.
2-for a specific material spectograhy is a modern method. (NDT).

 

[WKTaylor]

ksmith22..

DOD-HDBK-249 has chemical segregation tests that may be of value for "simply" differentiating between iron and steel. Regards, Wil Taylor

 

[Tankman650]

Have you thought about a hardness tester??? I have used it to determine the difference between carbon steel and cold rolled steel. The results can be used to determine the UTS of the material and should be able to determine cast iron vs cast steel.

 

[quadswift]

Keith,
As with most problems, it is best to solve them as near to the root cause as possible.

Why are you spending time and money to verify your supplier's product?

Do you specify / get 3.1b certification with the product?

I assume that you are sampling because you have some doubt about your supplier's ability to supply to the requirements. Or you have found some non-conforming parts? If you have no confidence in that part what about the rest?

Assuming you are specifying clearly / correctly and you have evidence of non-compliance -

I would trundle off to the supplier and have a look at his system of:
transferring your specifications,
specifying when raising his PO's,
receipt inspection against purchase order requirements,
traceability during manufacture / assembly,
certification.

It his his responsibility to supply you with what you specified.
Fix it for once and for all, raise your confidence level in the product,save yourself time and money.
(find / threaten to find another supplier)
Regards,
Quadswift

 

[Hush]

Quadswift,

By aftermarket I assume Kevin means used. I.E. the supplier is the customer not the person you want to tell fix it or we'll go somewhere else.

 

[AEF]

A lot of good responses. The difference between cast iron and steel is the carbon content. Iron with a carbon content between 2-6.67% is cast iron, less than 2% and it's steel. Hardness testing is one way to try and sort the materials but it would have to be a Brinell test and your availability problem seems to prohibit this. Spark testing also is a good sorting tool but this is a desructive test. Chemical spot tests are available in kit forms but testing for % carbon is very difficult and I'm not sure anything is available. The only sure fire method that is reasonably non-destructive, non-invasive and accurate is the use of an alloy analyzer that has the ability to test for % carbon, usually optical emission spectrometer types. Check out the web under Alloy Analyzer. Good luck!!

 

[metman]

Hardness test is not a valid comparison. You could have the same hardness for cast iron and steel depending upon the grades and temper. Spark testing is not all that destructive. With a fair amount of caution only a minimal amount of material needs to be removed to obtain a valid reading.

How to get a valid reading? Here is a very simple and economical procedure:

1) Buy some known material from a supplier.
a) One piece of Steel according to the composition
that you know is normally used. There is no such
animal as ductile steel. There is such a thing as
Ductile Iron which is a variety of Cast Iron.
there are also cast steels but this is a side issue.
You are trying to determine chemistry rather than
whether the item is cast or wrought. You do need to
know exactly what grade of steel for a valid
comparison.
b) One piece of Cast Iron. As with the steel sample,
you need to know what type of cast iron is
normally used. The main types are Gray, White,
Malleable, and Ductile (or Nodular) Iron.

2) Now spark your known samples as Rjeffery reccommended and you will see a distinctly different spark pattern between the steel and cast iron. As AEF said, "Iron with a carbon content between 2-6.67% is cast iron, less than 2% and it's steel" However, in your case, if it is steel, it will most likely have less than 0.5% Carbon for this application and therefore the distinct difference in spark pattern betwen .5% C and at least 2% C.

3) Now you have a STANDARD spark appearance or pattern to compare with your unknown sample (the one your customer sends to you).

4) Now spark your unknown part and compare the pattern with your two knowns.