Crack Detection of Elevator / Escalator Panel

can you just attach a photograph/ sketch of the area where you want to detect the crack ?

The possible techniques are LPI, MPI, Eddy Curernt test, all are feasible for the material.

LPI is always universal and may come out to be cheaper, and the sensitivity will be OK for you.

MPI and Eddy depends on the geometry- for that sketch is required.

For very small crack detection (may not be necessary for you) you need flourescent LPI (to be done under UV lamp)

LPI- Penetrants enters the crack. Then is wiped off and developer (usually chalk powder sprayed). The penetrant oozes out (like blotting paper of our olden times) and stains the chalk.

Requirement- crack should be able to accommodate the penetrant - should not be closed lipped (not expected in your case), should be able to wipe out the penetrant- that you have to study from your job, usually enough sensitivity if carefully done. Low cost. Water washable also available but the sensitivity is less, since usually water has less inclination to enter small crevices.

MPI/ Eddy test- Better sensitivity. If carefully done even microcracks may be identified. Can identify close lipped and sub-syurface cracks. But should be able to properly magnetize the area under inspection. Esopecially difficult if teh area is complicated.

I propose the LPI provided the penetrant can be wiped off with a cloth.

PS: for a small area like this, both are well within your budget (though I don't know the ongoing rate at your area)

i would try to apply heat source from one side and use infrared camera from other.i think it will work.good luck

You may want to look into ultrasonic methods for detecting cracks

UT has its own limitation (as Radiograghy has ) in identifying early fatigue cracks.

Usually preferred methods as mentioned in the first post is MPI (sensitive), LPI (a bit less in sensitivity as well as cost) - or the new techniques like AE (acoustic emission)

Hi,

"Magnaflux" offers broad range of crack detection methods and extensively used universally to detect cracks. This a standard NDT check recommended in Aero Space industries.

Go through http://www.magnaflux.com/products/overview.stm to get comprehensive idea.

Best of luck.

Generally speaking, to specify a crack detection method you need to know what material is and what service/load cases in order to assume what you must search.

You say it's "steel" but don't clarify what steel type (austenitic? ferritic/martensitic?) If the steel is ferromagnetic, magnetic particle inspection could work and is relatively faster and reliable than dye penetrant inspection. Furthermore, the geometry of one of those panels with many deep parallel grooves (anti-sliding) makes dye penetrant a bit difficult. The excess penetrant removal phase can be complicated unless you use a water washable technique.

Eddy current inspection should work fine, but the technique must be well selected to accommodate the sensitivity to the rather complicated geometry and the type of steel (ferro or non ferromagnetic).

Before subcontracting the service you must either know what crack type can have been grow due to your knowledge of the manufacturing process/service conditions or you should include then this in the scope of the work to be done by the laboratory (first determine what must they look at and then select the method).

Kind regards

Disclaimer: This method is not scientific, not conclusive and probably wouldn't hold up in a court of law but it is easy and free and may or may not quickly sort out almost any cast item.

Support the item on two knife edge like supports or three pointed supports or if the item is light enough or you have a cable strong enough, hang it so it swings free. Then hit it with a hammer and listen to it ring. If you have another known good item just like it, compare the ringing. If you are still not sure or want to distance yourself a bit from legal liability, then throw money at it with the method of your choice.

My preference for the type of casting you have is ultrasound since it has a multitude of points where stress risers can occur where penetrants might be difficult to be located visually and magnetized particles would be affected by intersecting eddy currents, just like the problems encountered when powder coating tight corners.

You are wrong.

It IS SCIENTIFIC IS CONCLUSIVE etc (I am shouting )

Only if you don't listen.

This is called Acoustic Emission Test and is a type of NDT - one of the I f I remember nine approved methods of ASNT - (only you check the vibration frequency with a probe ) and then it is not free .

I stand corrected.

Thank you.

I agree, but Acoustic emission is a relatively new term (I have some SNT-TC-1A editions in which AE is not included) and need to load the item to "hear" the noise. When I was a child I remember when trains stopped in any station, I saw some workers with a hammer hitting the flat end of wheel axles. They could appreciate by the sound frequency produced if there were fatigue cracks in the axle section changes. I was then very surprised and wondering what would those men do.

When I studied NDT I understand it!!

Kind regards

You may wish to look at the accoustic instrumenting experience and resources of -

Vic Kelly, Owner

Dave Kailer, Office Manager

NDT International, Inc.

711 S. Creek Road

West Chester, PA 19382 USA

Tel: 610-793-1700

Fax: 610-793-1702

www.ndtint.com

Accoustic would be the first check, then if the part fails look at other methods where you will probably have to check each side of the piece individually. The accoustic with multiple sensors in a NDT fixture may narrow down where the problem is, reducing the time to locate and repair.