Convert DWG to CATPART

A CATIA V5 workflow may require a DWG design to be delivered as a native .CATPart for part editing, assembly use, or engineering exchange. The correct conversion depends on whether the DWG contains only 2D drafting geometry or an actual 3D solid.

What the DWG format is

DWG is the native drawing format associated with AutoCAD and is also created by BricsCAD, DraftSight, ZWCAD, and other CAD systems. It can contain 2D lines, arcs, dimensions, text, blocks, layers, external references, meshes, surfaces, and, in some workflows, ACIS-based 3D solids.

DWG is used for architectural plans, manufacturing drawings, site layouts, fabrication details, and engineering documentation. A file that appears three-dimensional may contain only 2D projected views; front, top, and side views do not constitute a 3D model that can be converted into a solid CATIA part.

What the CATPART format is

.CATPart is the native part-document format used by Dassault Systèmes CATIA V5. It stores CATIA geometry, bodies, sketches, features, parameters, and, when modeled natively, design history such as pads, pockets, fillets, and patterns.

A CATPart can be inserted into CATIA assemblies and used for downstream tolerancing, machining preparation, and analysis. Imported geometry normally becomes a solid or surface body without the original feature tree, constraints, parameters, or design intent.

How to convert a 2D DWG

1. Open a copy of the DWG in AutoCAD, BricsCAD, DraftSight, or another compatible DWG editor.
2. Run AUDIT, repair errors, check the drawing units with UNITS, and remove unneeded layers, blocks, hatches, and annotations. Bind or package external references if they are required.
3. Save the required geometry as a DXF version supported by the installed CATIA V5 release. DXF is generally more suitable than DWG for 2D exchange, but it does not contain the missing 3D design information.
4. In CATIA V5, use the Drafting workbench’s DXF/DWG import function, commonly available through Tools → Import External Formats. The exact command and supported DXF versions depend on the CATIA release and installed licenses.
5. For a true 3D part, create a new CATPart and use the imported curves as sketch or reference geometry. Close open contours, correct duplicate or projected entities, verify scale, and build pads, pockets, revolves, or other features.
6. Save the reconstructed model with File → Save As, using a name such as converted_part.CATPart.

This is reconstruction rather than direct conversion. A 2D drawing does not provide reliable depth, feature order, parametric constraints, or complete manufacturing intent.

How to convert a DWG containing 3D data

1. Inspect the DWG in the authoring CAD system and confirm that it contains real solids or surfaces rather than view geometry, blocks, meshes, or 2D projections.
2. Export the model from the authoring system to STEP, preferably AP214 or AP242, if that system supports STEP export. Export separate components separately when the file contains multiple parts.
3. Open the .stp or .step file in CATIA V5 with File → Open, or use the STEP import command provided by the installed CATIA configuration.
4. Verify units, orientation, body count, face continuity, and solid status. Use CATIA healing, join, or surface-repair tools when the translator produces gaps or fragmented faces.
5. Save the imported result as model.CATPart. Depending on the CATIA release and translator license, the result may be a usable solid, a set of surfaces, or other imported, non-parametric geometry.

AutoCAD itself may not provide native STEP export in every edition. If the source application cannot export STEP, use its available neutral format, such as SAT, or a commercial translator that explicitly supports the required DWG entities and CATIA V5 output.

Desktop and online conversion tools

For desktop translation, CAD Exchanger Desktop and Datakit translators are options to evaluate. Their supported DWG entities, CATIA V5 export capability, CATIA release compatibility, and licensing differ, so confirm that the exact input objects and .CATPart output are supported before purchase.

ODA File Converter is useful for changing DWG versions or producing DXF, but it does not create CATPart files. Generic online converters also rarely provide dependable DWG-to-CATPart conversion because CATPart is a proprietary, version-dependent native format. A cloud service such as CAD Exchanger Cloud should be considered only if its current format list explicitly includes both the required DWG input and CATIA V5 part export; do not upload confidential CAD data without reviewing retention and data-processing terms.

Quality and compatibility limitations

• 2D import does not create a 3D part. It transfers drafting curves and annotations; solid modeling must be rebuilt in CATIA.
• STEP usually transfers boundary geometry more reliably than interpreting arbitrary DWG entities, but normally loses feature history, sketches, constraints, and parameters.
• Check units explicitly. A millimeter-to-inch mismatch can produce a valid-looking part at the wrong scale.
• Expect issues with splines, proxy objects, blocks, external references, custom fonts, hatches, meshes, and unsupported ACIS entities. Convert or explode only the objects required for exchange.
• CATPart files are version-sensitive. A file saved by a newer CATIA V5 release may not open in an older release; save in the recipient’s supported version when possible.
• Always compare the converted model with the source drawing or solid, including dimensions, hole locations, thicknesses, orientation, and component count.