Polyurethane inspection - Ultrasonics? 1

[JCovey]

We are using a part that consists of polyurethane molded into a channel in a metal ring. The channel is .375W x .438DP. The molding company is having problems removing the air from the base of the channel and it's causing us problems.

Is there a way to perform NDT on these parts for QC purposes? I hoped to use ultrasonics, but I'm not able to get our unit to function with urethane. Does this material have too much sound attenuation?

I believe the urethane is compounded to a duro 90A.

Thanks,
JC

 

[akat]

what UT equipment are you using? A log amplifier with your UT equipment would help a great deal for high attenuation materials.

Thanks,

AK

 

[JCovey]

akat,
We're using a very basic panametrics unit, Model 26, with a 5MHz dual element transducer. This model has a digital display. I think that the proper transducer may help, but I'm not even sure a transducer will overcome the limitations of our base unit.

Any thoughts on what transducer may be a better fit?

Thanks,
JC

 

[polleke]

Why donot you make an X-ray on that part?
For ultrasonics you need much energie and you need to get a reference.
X-ray is easy done on this soft material
Polleke

 

[jrhols]

Inspection will not solve the underlying problem.
First define the problem, is air the problem?
Then you have to modify venting of the mold.
Problem identification and inspection exist, but the decision must be made and inspecting only tends to support a previous existing opinion. That is why inspecting would be the wrong way to approach this kind of problem.
Think more mathematically. If a therum exists, then it
does not confict with other therums, otherwise one is wrong.
Inspection is the same way. NDT methods are invented
for much bigger cost obsticles, which is the main reason
inspection is so misunderstood and widely oversold.

 

[BillPSU]

jrhols is correct.

You may have to drill a small hole in the ring and allow air a way to escape. Probably what you didn't want to hear but venting is a condition of any injection mold and in this case the ring is the mold.