ultrasonic flaw defector for casting

[dogbural]

Hi,

It is proposed by our casting foundry that they perform a pre-machine of the casting such that any defective parts (void, porosity, cracks) can be detected after pre-machining.

At first thought, this is a good idea. Then, in my second thought, can they use any kind of detector to detect flaws? Since its geometry is not as complicated, it could be worthwhile to try.

Is there any good model you would recommend?

Thanks

 

[MJCronin]

Common NDT Inspection Methods Used on Castings:

-- Ultrasonic Inspection. Ultrasonic inspection methods have been developed to detect cracks or other abnormalities within the casting, with high accuracy. These methods ar relatively cheap and quick
-- Radiographic Examination. Somewhat expensive and tedious
-- Visual Inspection: Not suitable for internal voids or other defects

When you say: "can they use any kind of detector" what exactly do you mean ?

Does ultrasonic NDT not suit this purpose ?

MJCronin
Sr. Process Engineer

 

[IRstuff]

No, cannot use "any" detector, nor "any" source; frequency range of interest is in the 500 kHz to 1 MHz range

https://www.olympus-ims.com/en/appl...uman hearing extends to a,500 KHz to 10 MHz).

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[EdStainless]

Do you understand how UT works?
Do you have any experience with UT?
Do you have anyone with an ASNT certification?
You will need to couple the UT probe to the casting either by putting in a tank of water or by using a gel on the surface.
The position and angle of the probe matter a lot.
Will this be manual or will you use a robot to do the testing?
And what will you use for reference standards?
You can likely find a consultant to help with this process.

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[bobjustbob]

Due to the shapes involved in our castings and the difficulties using UT on a rough cast surface with irregular thicknesses and shapes we rarely employed it. Most commonly, for surface flaw detection, mag particle inspection either wet or dry for steel parts and dye penetrant for stainless. UT tends to be much slower and more expensive than either of these methods. For subsurface indications, we would use radiography. While expensive and time consuming it would provide better detection than UT.

Bob

 

[mfgenggear]

yes for either NDT testing mention on previous post it is necessary to rough machine to an acceptable
micro surface finish, because it will not be able to complete any test

 

[mfgenggear]

I was once a NDT inspector,
so penetrant is for any surface or slightly subsurface indications. EG pores, cracks, linear indications, laps, and seams and so on.
Xray is for sub surface indications similar as above, mostly used for inspection of welds.
UT is as reliable as the rest in the hands of the right technician inspector. and the with a high level of experience. in order to calibrate it. it has to have a sample with known imperfections.

 

[EdStainless]

We used to cast a non-magnetic alloy in rather complex parts.
There were some known locations in castings where we had issues from time to time.
We would rough machine the parts and then use UT to test this one location for issues.
We had fixtures that would let us locate the transducers in repeatable locations.
We just did it in a tank of clean water.
We had reference parts, some with actual casting defects and some with indications of know size machined in from the back.
In otherwards, if you can do this with Mag-Particle or Dye-Pen then do it.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed