In the past I’ve tried to use some models exported from Solidworks and Inventor. When I looked at them in Max I always had to do a LOT of manual cleanup of the mesh. One of the big problems is ridiculous N-gons, and ideally you want quads and tri’s. I’m sure the UV’s will probably be a mess too. The problem is that parametric solid modelers are so very very different from what we use to model game/entertainment/art models. If you start talking about UV’s, edge loops, polygons etc to most(not all) CAD guys you will most likely just draw a blank stare, they almost never have to worry about any of this stuff.
Anyhow, check your topology, its likely a real mess.