Conversion from Navisworks to IGES is not supported yet :(

Navisworks

Navisworks is a native file of Navisworks® project review software by Autodesk.

Navisworks files come in three formats: NWD, NWF, and NWC. An NWD is a single file that contains all model geometry, environment, viewpoints, and review markups. An NWF file is a list of links to the original files. It doesn't keep model geometry and, to be opened, requires access to the original CAD files. An NWC is a cache file created from any native CAD or laser scan files, when opened in Navisworks.

IGES

IGES (Initial Graphics Exchange Specification) was among first vendor-neutral CAD formats designed to enable interoperability between different CAD systems. The latest versions of IGES have been approved by ANSI (American National Standards Institute) and published by US PRO (U.S. Product Data Association). The latest officially approved version of the IGES standard is version 5.3 which was published in 1996. Nonetheless, IGES remains a broadly used format (along with STEP) supported by all major CAD/CAM/CAE systems such as CATIA, Autodesk Inventor, Solidworks, Solid Edge, NX, Pro/Engineer, Creo and multiple others. IGES files usually have *.igs or *.iges file name extensions.