Convert CATPART to STEP

A supplier, customer, CAM system, or neutral CAD viewer may require STEP instead of native CATIA data. Converting the file provides interoperable geometry for inspection, manufacturing, or editing in another CAD system.

What the CATPART format is

.CATPart is Dassault Systèmes CATIA’s native part-document format, used primarily by CATIA V5 and compatible 3DEXPERIENCE workflows. It can contain parametric features, sketches, constraints, bodies, hybrid geometry, materials, annotations, and references to external documents.

CATIA users create CATPART files in Part Design, Generative Shape Design, and related workbenches. The file is common in CATIA-based engineering departments, supplier exchanges, product archives, and assemblies whose component links reference CATPART documents.

What the STEP format is

STEP is the ISO 10303 neutral CAD format, usually stored with a .stp or .step extension. It is supported by major mechanical CAD systems such as CATIA, Creo, NX, SolidWorks, Inventor, Fusion, and FreeCAD, as well as many CAM, inspection, and manufacturing applications.

STEP normally transfers boundary-representation solids and surfaces, but not CATIA’s editable feature tree, sketches, formulas, design tables, or update history. AP242 can carry product-manufacturing information and is a suitable choice when both applications support it. AP214 or AP203 may be more compatible with older receiving systems.

How to convert the file

Using CATIA

1. Open the CATPART in CATIA. Resolve required external links and confirm that all intended bodies and surfaces are present.
2. Hide construction geometry, reference elements, and bodies that should not be exported. Save a copy if the source model must remain unchanged.
3. Configure the STEP translator through Tools → Options → General → Compatibility → STEP. The menu location, available AP standards, and export controls vary by CATIA release and license.
4. Use File → Save As, choose STEP as the output type, and save the file with a .step or .stp extension.
5. Select AP242, AP214, or AP203 according to the recipient’s software. Enable PMI or other product-data options only if the receiving system supports the same information.
6. Reopen the exported file in CATIA or a different CAD application. Check units, body count, holes, fillets, free-form surfaces, and dimensions that affect manufacturing.

CATIA’s STEP export requires an installation and configuration that includes the relevant translator. A CATIA installation that can open CATPART files does not necessarily provide every available STEP export option.

Without CATIA

CAD Exchanger Desktop can convert CATIA V5 CATPART files to STEP when the installed version lists both formats as supported. Import the CATPART, select the required bodies or components, choose STEP and the available AP standard, then export.

Datakit CrossManager is a commercial translator suited to scripted or batch conversion. Check its current support matrix for the CATIA release, file type, and model features before purchasing or processing a production archive.

Online services such as CAD Exchanger Cloud can handle non-confidential files when their current format list explicitly includes CATPART input and STEP output. Upload the file, select STEP and the required AP standard, convert it, and validate the download locally. Do not upload proprietary designs, personal data, or files restricted by a supplier or customer agreement.

Quality and compatibility limits

• A CATPART-to-STEP conversion is generally a geometric translation. The resulting model usually cannot be edited through CATIA’s original feature parameters or design history.
• Exporting one CATPART produces one part document. A CATProduct assembly needs separate assembly-export handling and may become one STEP assembly, a merged shape, or multiple component files depending on the CATIA settings and receiving application.
• Verify units explicitly. STEP can store unit information, but an importer with incorrect settings can display or process the model at the wrong scale.
• Small faces, tight fillets, zero-thickness regions, self-intersections, invalid solids, and poorly joined imported surfaces can cause translation failures. Run CATIA geometry checks and healing tools before export, then inspect the STEP file for gaps, missing faces, and invalid bodies.
• STEP is not automatically smaller than CATPART. It stores explicit boundary geometry rather than CATIA’s parametric definitions and may therefore produce a larger file.
• Confirm AP242 PMI support on both sides when annotations, tolerances, or manufacturing information must survive. Use AP214 or AP203 when shape exchange is the priority and the recipient has older STEP support.