Convert CATPART to OBJ

Blender, rendering tools, web viewers, and some mesh-processing pipelines accept OBJ but cannot use CATIA part data directly. Exporting a .CATPart as OBJ creates a portable polygon mesh for visualization, downstream editing, or delivery to systems outside CATIA.

CATPART and OBJ formats

CATPART is the native part-document format of Dassault Systèmes CATIA V5. A .CATPart can contain feature history, sketches, parameters, solid and surface geometry, and links to other CATIA data; it is a parametric CAD document rather than a mesh file.

CATIA V5 is used heavily in mechanical design, aerospace, automotive, tooling, and product development. A part that belongs to an assembly is normally referenced by a .CATProduct assembly document; converting one CATPART does not export the rest of that assembly.

OBJ is a text-based Wavefront polygon-mesh format. It stores vertex positions, faces, normal vectors, and texture coordinates, while a separate .mtl file can define basic material assignments and texture references.

OBJ imports into Blender, Autodesk Maya, 3ds Max, Cinema 4D, MeshLab, and many rendering and asset pipelines. It does not retain CATIA features, dimensions, constraints, exact B-rep or NURBS surfaces, assembly relationships, or CAD-editable parameters.

Convert with CAD Exchanger Lab

CAD Exchanger Lab is a suitable desktop converter because it reads CATIA V5 CATPART files and exports OBJ without CATIA being installed. Confirm that the installed version supports the CATIA V5 release used to create the source file.

1. Open the .CATPart in CAD Exchanger Lab with File → Open.
2. Inspect the viewport and model tree. Hide construction geometry, unwanted bodies, or components before export.
3. Choose File → Export and select Wavefront OBJ (.obj).
4. Set the tessellation tolerance or quality. Use a smaller chordal deviation for visible curved surfaces, fillets, text, and small holes; use a coarser tolerance for lightweight viewing models.
5. Export normals and materials when offered. Keep the generated .obj, .mtl, and any texture files in the same folder.
6. Open the OBJ in the receiving application and check orientation, dimensions, missing faces, and smoothness.

For occasional work, CAD Exchanger Cloud provides browser-based CATPART-to-OBJ conversion. Do not upload confidential, controlled, or export-restricted CAD data until the service's storage, retention, access, and contractual terms have been approved.

CATIA and mesh-export fallback

If CATIA is available and a direct OBJ exporter is unavailable, export the part as STL from the CATIA installation, then import the STL into Blender and use File → Export → Wavefront (.obj). This produces an OBJ mesh, but STL carries neither materials nor texture coordinates; use a direct CATPART-to-OBJ converter when material assignment matters.

Open a .CATProduct, rather than an individual CATPART, when the required output is a complete assembly. Export it as a combined mesh or as separate objects according to the receiving application's requirements.

Mesh quality and compatibility

OBJ represents the CAD model as approximated polygons. Threads, tight fillets, embossed markings, thin walls, and small holes need finer tessellation, which increases polygon count, conversion time, and file size.

OBJ has no standardized unit field. CATIA designs are commonly authored in millimetres, while a target program may treat OBJ coordinates as metres or scene units. Measure a known feature after import before scaling the mesh.

OBJ material support is limited compared with CAD appearance data. Colors, layered materials, procedural appearances, and textures may be simplified, omitted, or require relinking through the adjacent .mtl file.

Keep the original .CATPart as the engineering master. The OBJ is a derived mesh and cannot be converted back into an equivalent parametric CATIA model.