To Import an AutoCAD 3D DXF File
1. Click File > Open without a part or an assembly open. The File Open dialog box opens.
2. Select DXF (*.dxf) in the Type box. The DXF files in the working directory appear.
3. Select the DXF file you want to import or browse to find the file.
4. Click Import. The Import New Model dialog box opens. The default import type is Drawing.
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Assembly is the default when the  DXF file contains at least a single 3D solid entity.
5. Select Part or Assembly to import the faceted or embedded ACIS geometry.
If the DXF file contains embedded ACIS geometry, you can only import the file as a new assembly or an assembly component.
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Do not import the DXF file with the embedded ACIS geometry as a feature or a new part.
6. Select an import profile from the Profile list or retain the import profile in use. Click Details to open the import profile editor, DXF — Import Profile, and customize the import profile settings, if required.
7. Click OK in the Import New Model dialog box. The Layer Import Options dialog box opens if you clicked Customize layers in the Import New Model dialog box.
8. Select layers for import and set their import status in the Layer Import Options dialog box. The DXF part or assembly file is imported. The import log file is automatically generated in the working directory.
If you select Part as the import type, the faceted data merge to form a single faceted representation in a single import feature.
If you select Assembly as the import type, the faceted data form part components of subassemblies represented by layers.