The material web is guided through {HEAD ~ a gap} between {TAIL ~ the sonotrode} and the counter tool and acted upon by the sonotrode 
between
The material web is guided through { HEAD ~ a gap } between { TAIL ~ the sonotrode } and the counter tool and acted upon by the sonotrode
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH