SolidWorks can export its own formats (including the assembly SLDASM) to many other CAD formats like the IGS/IGES. If you do not have access to Solidworks, then the only option would be use some dedicated CAD conversion software like the CrossManager.
Convert SolidWorks assembly data to IGES 3D exchange format.
We found 9 software records in the database related to .sldasm to .igs file format conversion.
Microsoft Windows software - convert sldasm to igs on Windows
A 2D and 3D CAD construction software
Convert from sldasm file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned sldasm to igs. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Leading 2D and 3D CAD development software from Autodesk
A CAD converter with huge format support
A widely-used 3D animation application from Autodesk
A set of 3D modeling tools
A 3D CAD translation softwate
A dedicated CAD converter
A CAD visualizaton, analyzation and translating system