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-   -   Internal Flaw detection ??? (http://www.plctalk.net/qanda/showthread.php?t=113596)

milmat1 January 3rd, 2018 12:29 PM

Internal Flaw detection ???
 
Hey friends,

I want to see if anyone has any experience with internal defect / flaw detection.

I have an application where we will pick and place product and during the process we must inspect this product. Vision system can detect external flaws such as chips or cracks etc. But I need a way to detect internal flaws in a "brick" such as internal voids or cracks not visible from the exterior.

Does anyone have any experience or suggestions for how this can be done.?

scott.lawrence January 3rd, 2018 12:35 PM

x-ray system, maybe?

dwoodlock January 3rd, 2018 12:36 PM

Literally a brick?

jstolaruk January 3rd, 2018 12:36 PM

Look into Eddy Current inspection - used for crack detection and thread detection.

dwoodlock January 3rd, 2018 12:38 PM

EC is for metals and the depth of penetration is not great in a lot of cases. Depends on the specifics of your application. If its literally a brick(non-metallic), It wont help you.

jstolaruk January 3rd, 2018 12:40 PM

Other method I've used is sound. Literally pinging the object with a hammer and evaluating the responding sound made for non-normal conditions using signature analysis.

jstolaruk January 3rd, 2018 12:41 PM

Quote:

Originally Posted by dwoodlock (Post 763876)
EC is for metals and the depth of penetration is not great in a lot of cases. Depends on the specifics of your application. If its literally a brick(non-metallic), It wont help you.

Correct - it would be nice if the OP was more specific.

jrexrode January 3rd, 2018 12:49 PM

Maybe ultrasonics if the material lends itself to that. Would have to use some sort of interface coupling between the material and the transducer. This has been used to detect defects in railroad steel for a long while now.

dwoodlock January 3rd, 2018 12:53 PM

There is a method that I've been introduced to over the past couple years called capacitive inspection. If you google it, there are various articles about it. I think its pretty versatile and can be used on metals, or concrete. I have not yet had an application where we bit into it, but from the information I saw, and the trials we ran, it looked promising.

This paper is specifically geared at concrete structures.

http://mitpublications.org/yellow_im...246_logo_6.pdf

milmat1 January 3rd, 2018 01:48 PM

Yep !
Literally a brick. But its a type of firebrick. Very uniform smooth and clean, straight from the kiln..

I though we would pick it with a robot and present it to an inspection camera for the general inspection. However the customer has specified that we detect "Internal Flaws". I can only imagine that an internal flaw would have to be a void or a crack..

milmat1 January 4th, 2018 08:01 AM

Quote:

Originally Posted by jstolaruk (Post 763875)
Look into Eddy Current inspection - used for crack detection and thread detection.

It appears that eddy current NDT is mainly used to inspect the inside of a bore tube or hollow shaft etc. As the probe is inserted into the DUT...

janner_10 January 4th, 2018 08:11 AM

I would be onto the customer, asking them to define internal flaws prior to speculating about what to inspect them with.

jstolaruk January 4th, 2018 08:35 AM

Quote:

Originally Posted by milmat1 (Post 763985)
It appears that eddy current NDT is mainly used to inspect the inside of a bore tube or hollow shaft etc. As the probe is inserted into the DUT...

It might, but I've used it primarily for thread and crack detection. Any place where a change in the magnetic field created and measured by the sensor.

dwoodlock January 4th, 2018 08:47 AM

Quote:

Originally Posted by janner_10 (Post 763989)
I would be onto the customer, asking them to define internal flaws prior to speculating about what to inspect them with.

+1 to this.

Make sure they provide examples(Masters) of things they want to catch, otherwise your in for an endless # of complaints.

milmat1 January 4th, 2018 12:45 PM

Quote:

Originally Posted by janner_10 (Post 763989)
I would be onto the customer, asking them to define internal flaws prior to speculating about what to inspect them with.

I have requested that they define "Internal flaw" what does that mean ?
If its just a void they are concerned with I could simply weigh the piece. I cant imagine a void making it through the kiln without crumbling or exploding. And I don't think there is any chance of a foreign object being inside it.. So yeah they need to define exactly what I am looking for...

Thanks


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