Convert CATPART to STP

A manufacturing partner, CAM or inspection system, or CAD application may require a STEP file instead of CATIA’s native part document. Exporting the part as .stp exchanges its 3D geometry in a widely supported neutral format without giving the recipient the editable CATIA model.

CATPart format and its users

CATPart is the native single-part document format of Dassault Systèmes CATIA V5. It can store solid and surface geometry, a parametric feature tree, sketches, parameters, materials, properties, and links to other CATIA documents.

CATIA V5 is common in aerospace, automotive, industrial equipment, and supplier engineering. A .CATProduct assembly normally references multiple .CATPart files; converting one CATPart exports only that part, not the assembly structure.

STP and STEP format

STP and STEP are interchangeable filename extensions for ISO 10303, the Standard for the Exchange of Product model data. STEP transfers boundary-representation solids and surfaces between CAD, CAM, metrology, and visualization systems.

STEP AP203 provides basic geometry and assembly exchange. AP214 can retain presentation attributes such as colors and layers and remains widely compatible. AP242 adds newer product-data capabilities, but the receiving system must support the selected protocol. STEP does not retain CATIA feature history, sketch constraints, or reliably preserve CATIA-specific parameters and links.

Export with CATIA

1. Place the .CATPart file and any required linked documents where CATIA can resolve them. Open the part and update it so the displayed geometry is current.
2. Run CATIA’s geometry check if the part will be machined or manufactured. Repair invalid faces, open surfaces, or failed updates before export.
3. Choose File → Save As, select STEP from the file-type list, enter a filename such as bracket.stp, and save the file.
4. Select AP214 when the recipient needs colors or uses older CAD/CAM software. Select AP242 only when both CATIA and the recipient explicitly support it.
5. Open the exported file in the destination CAD system or an independent STEP viewer. Check body count, holes, cavities, fillets, surface continuity, dimensions, and any required colors.

If STEP is absent from CATIA’s Save As list, the installed CATIA configuration may lack the required STEP interface or license. Use the organization’s CATIA administrator or a licensed translation tool rather than renaming the file extension.

Desktop and online conversion options

CATIA is the preferred converter because it reads the native part directly. When CATIA is unavailable, use a translator that specifically lists CATIA V5 .CATPart import and STEP export for the relevant CATIA version. CAD Exchanger Lab and TransMagic are established desktop options; import support can vary by source-file version, licensing, and installed translation modules.

CAD applications such as SOLIDWORKS may open CATIA V5 files when the required importer or 3D Interconnect configuration is available, then export STEP through File → Save As. Do not assume that FreeCAD or every general-purpose CAD program can import CATPart files directly; many require an external translator.

For a simple, non-sensitive model, CAD Exchanger Cloud is a reputable browser-based option that supports CAD translation subject to its current format and account limits. Confirm that the service accepts the CATIA version and offers STEP output before uploading. Do not send export-controlled, confidential, or contract-restricted geometry to a public conversion service.

Compatibility checks

A translated STEP model is normally an imported, non-parametric body. The recipient can measure it and perform direct edits, but changing a CATIA pad, pocket, sketch dimension, or design rule usually requires remodeling or access to the original CATPart.

Verify units with a known dimension after import. STEP carries unit information, but CAD import settings and document defaults can still produce an unexpected scale interpretation.

For assemblies, open the parent .CATProduct in CATIA and export the assembly as STEP if the recipient needs component hierarchy and placements. CATIA assembly constraints, external references, and application-specific metadata should not be expected to transfer.