Thanks for all the replys. I think what flanakins suggested might work. Atleast it would be worth trying for. Delelting, deactivating or copy/paste is no option in this case, because there are lots of visible and hidden surfaces. So that would require too much extra work.

I'm not so sure about the wrapping-tool in this case. There isn't so much parameters that you can chancge. Basically the only adjustable value is Grain. In this case the product is physically so big that smallest Grain-value Catia lets me use is 10mm. That makes all the sharp edges round and unaccurate. Basically that is no problem, but the way how the rounded surfaces are created makes the model very big and clumpsy. In smaller products all parts that propably is the best/fastest solution.

But I will try on the assembly->allcatpart->STL method. And if that works I'll let you know