What exactly is Sonic Welding?

Hi.

We have a job of approx. 5000 nos. It is a small logo with intricate details that needs to be put onto fabric in single color . On the sample provided by the customer, the image is raised by about 1mm and is extremely sharp and clear.

We made a submit using Dow Corning Silicon ink +HD Base. I am not too pleased with the result as the main difference is the logo is not as crisp and sharp as the client sample. The other issue is when we take a close look at out sample, on the top surface we see think lines ( i guess it's caused by making so many impressions through the screen). The client's sample is absolutely flat on the top with a very smooth feel.

Is there anything that I can change to get a better finish and smooth feel?

The client was mentioning something about their sample being welded and not printed. Some quick googling led me onto "Sonic Welding of Rubber onto Fabric". Is anyone aware of such a process?

Thanks in advance.

Rottweiler