Vibration Welding (Burr Issues).

[vivekigles]

Please Support !!!!

We are using a vibration welding machine manufactured by Branson (A division of Emerson) & we are facing the issue of burr on regular basis. To reduce the burrs we have tried to reduce the amplitude of the machine by 0.03mm but it did not help. I have attached some pictures of parts with burrs and Welding parameters set value vs result value.
We are using the process for Welding two plastic parts. (The surface where the weld is to be made is linear and smooth).

Please suggest what else we can try to resolve this issue.

 

[Compositepro]

Your results are what would be expected if you are trying to weld two flat faces together. You have to mold a raised bead in the center of one of those flat faces so that they touch only at the raised bead. Then the ultrasonic vibration melts this bead and the resulting flash welds the two faces together, without extruding out of the gap between faces. The bead causes the vibration energy to be concentrated in a mach smaller area resulting in reaching a higher temperature more quickly. As the bead melts, the area of contact increases and the plastic solidifies.

 

[Pud]

The second photo looks a very odd finish on the part. Is there a blowing agent added or is it moulded from very damp material? (ABS?)


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[vivekigles]

Thank you for your answers!
Reply to Compositepro: We cannot use beads on anywhere the part as this need to be leak proof weld. Later on the assembly is tested at 17 MPa pressure in such a way that no Leakage should be there.

Reply to Pud: The material we are using is Polybutylene Terephthalate (PBT-GF30-506).

This issue occurs randomly otherwise the welding is pretty smooth so, I'm hoping that without changing any design of part or jigs can we figure out something with the parameters??

 

[3DDave]

Ok - instead of a bead, call it a molded-in raised ridge on one part and that raised ridge will become the melted plastic that seals the finished weld.

Also - 17 MPa? That converts to 2500 psi, which is hydraulic service pressure. Is this for a submarine duty?

 

[vivekigles]

@3DDave Thanks for the answer.

Raised ridge available on the child part.

Yes, This is for hydraulic service duty, sorry I cannot disclose much details.