"When you have a joined object, if you uncheck that "Weld vertices along edges" option, it will still produce a watertight no-crack mesh but the mesh will be clustered into separate non-connected (non-connected in a topological sense, but actually physically touching in location) sets of vertices with one set for each original surface. This will then allow you to use your polygon modeler's mesh processing functions to separate the mesh into individual objects."

I asked for the "mesh like joined" function, because I don't want to get all surfaces of a polysurface unwelded, only selected one. I need the meshes for a mesh unfolder (UV texture coordinates unfolding). Welded mesh parts are treated as one object and each unwelded connection is treated as cut in the mesh.

Attached an example of a seat cushion. I like to get separate side parts, but the mesh should be generated like from a closed polysurface. It's easier to extract NURBS surfaces than mesh parts. If I would disable the MoI weld function than I would get to much cuts in the mesh.

Thanks,
Micha