be seen that the incoming web 12 is significantly thicker than the outgoing ultrasonically treated web 44 when entering the gap 72 the incoming web 12 is compressed which can be seen from the portions 74 and 76 this compression either takes place automatically or with the help of additional guidance means not depicted furthermore the weld horn 14 may be significantly wider than the protrusion 24 there is generally no structure on the lower surface 70 of weld horn 14 the cross sectional configuration of the ultrasonically treated web 44 is shown in the enlarged portion b the fibers of web 44 have been ultrasonically joined at the portion 78 and there are smooth transitions 80 and 82 between the welded portion and the normal portion of web 44 furthermore it can be seen that the thickness of the ultrasonically treated web 44 is significantly smaller than that of the original web 12 resulting from the ultrasonic treatment it can also be seen that the welded portion 78 has indents on both sides the upper side and the lower side although only the protrusions 24 are in contact with the web 12 on the lower side however a total compression occurs which causes the upper portion to be compressed so that transitions on both sides 80 and 82 are observed 0041 fig8 shows an alternative.