BATCH UTILITY IN NAVISWORKS

In Home menu under Tools select Bacth Utility,

This will open Batch Utility tab

As explained in above image,

1. Browse the file location
2. Select the file type you want to convert
3. Select & add the files to get converted
4. Browse the output location
5. Finally hit Run, this will conver the bulk files to NWC & NWD format:)

The great tool just used for once the project where I had created Revit files for differenct phases(10 in number), saved my lot of time:)