ultrasonic welding of PET

I understand, your client wants to save the additional glycol coating and wants to weld PET direct. Plasma treatment should improve the ultrasonic welding:

According our experience, Plasma can improve it when it removes some hydrocarbons, p.e. release agents from the surfaces – In some application this increases the speed and quality – but it can not improve the compatibility itself. Up to now we could not weld new material together only be plasma treatment.

Plasma of course could improve the adhesion of the glycol and improve in this way the quality; you also can change to a UV Bonding after plasma treatment.