NDE/NDT check of ultrasonic polymer weld

[aspearin1]

I have some product failures I am evaluating. The product consists of ultrasonically welded plastic parts. The current release criteria for these parts is a manual "tug" on the parts to determine whether or not the weld is holding. Neeless to say, this practice is quite flawed, and I'm looking for a more automated approach. I am encouraged by some of what I see about ultrasonics for sensing these potential flaws. Does anyone have experience using ultrasonics to detect polymer weld flaws, voids or weaknesses? Does anyone have a preferred supplier of such devices, or interpreting software?

I see that pass-through detection (tranceiver and receiver on opposite sides of workpiece) as a common practice. My parts are rather low clearance, so I wonder if a reflectance or echo detection (transeiver and receiver on same side of work piece) will give me a useable signal. Again, please share your experiences if they apply.

Thanks in advance.
ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee


ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[roddypiper]

Hello,
I am just starting to look at buying a few ultrasonic welding machines. What brand of machine do you use, and are you happy with it's performance? It seems as thought there are a lot of companies that have similar machines.

Thanks.

 

[aspearin1]

We generally use Branson... but they are not without issue. We're also looking into Sonobond and Stapla for new projects. Based on customer service and technical representatives, I'm inclined to go with Stapla... but like you said, the machines are pretty much the same. So in my mind, service is key.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[CoryPad]

You can use ultrasonic reflection with polymers.

I recommend you contact the following companies:

GE Inspection Technologies

http://www.geinspectiontechnologies.com/products/Ultrasonics/FlawDetectors/index.html

Sonoscan

http://www.sonoscan.com/what_applications.html

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ledon]

I don't know the configuration of the part in question. but, if you can get a cross-sectional angle for ultrasonic inspection. Then a compresional wave inspection process (similar to a silverbraze bond inspection) may be better/cheaper than flaw dection. If the problem in lack of fusion/bond at the weld that is. The thickness UT machine is less expensive and easier to operate and train personnel to use.

 

[JimNDT]

Dear aspearin1:

Weld flaws and voids can be detected with laser optical inspection systems. This technique has proven success especially if composite materials and/or joints are concerned.
You might have a look at

http://www.dantec-ettemeyer.com

and follow the link to the NDT product lines.

They have sold especially in automotive aircraft industry, where your problem is quite actual.

If you are interested in the "strength" of your welded joint then it might be a solution to measure the strain & stress distribution of the area of interest on your component. Dantec have also a product line for measuring this. (follow the strain & stress link on their

http://www).

I am sure that they can provide help with your callenging task.

Regards
Jim