Convert CATPART to STL

3D printers, slicers, inspection applications, and mesh-based CAD tools often require STL instead of CATIA’s native CATPart format. Exporting creates a triangulated surface mesh for manufacturing or exchange, but removes the original parametric design history.

What the CATPART format is

.CATPart is the native part-document format used by Dassault Systèmes CATIA V5. It can contain parametric solids and surfaces, sketches, constraints, bodies, features, annotations, and other design-history data used by CATIA workbenches.

CATPart files are common in automotive, aerospace, industrial design, supplier, and CATIA-based engineering workflows. A CATPart normally represents one part; an assembly is commonly stored as a .CATProduct document that references one or more CATPart files.

What the STL format is

.STL describes surfaces as triangular facets. Slicers such as Cura, PrusaSlicer, and Bambu Studio use it for 3D printing, and inspection, prototyping, and mesh-processing applications support it as a simple geometry format.

STL is widely supported and binary STL is usually much smaller than ASCII STL. It does not retain sketches, dimensions, feature trees, assembly relationships, materials, colors, or most metadata. STL also has no formal unit field, so set or verify the units and scale in the receiving application.

How to convert the file

Using CATIA V5

1. Open the CATPart in CATIA V5 and update it. Resolve broken links, failed features, and geometry errors before exporting.
2. Display the body or surface to export and hide construction geometry, reference elements, and unwanted bodies. Select the intended result explicitly when the part contains multiple bodies.
3. Open the STL export function, usually through Start → Infrastructure → STL Rapid Prototyping, then choose STL Export. The exact workbench and command depend on the CATIA V5 release, configuration, and installed licenses.
4. Select the part or result, specify an output name such as part.stl, and set the tessellation parameters. CATIA commonly exposes chordal or sag deviation and, depending on the release, angular controls. Use a finer tolerance for curved or dimensional parts and a coarser setting for previews.
5. Choose binary output when supported, export the file, and inspect it in the target slicer or mesh viewer. If the STL workbench or command is unavailable, the CATIA administrator must install or license the required functionality.

Using CAD Exchanger Desktop

CAD Exchanger Desktop can import CATIA V5 files and export STL when the installed version supports the specific CATPart release. Open the file with File → Open, verify the imported body, then use File → Export or Save As and select STL. Set mesh resolution, output units or scale, and binary output if those options are available. Validate the result because third-party importers may handle CATIA versions, bodies, links, and units differently.

Using an online converter

CAD Exchanger Cloud is an option for nonconfidential files when its current format list includes the supplied CATPart version. Upload the file, choose STL, configure tessellation when offered, and download the result. Online support can vary by CATIA version, file size, linked content, and account tier, so verify the service’s current input requirements first.

Do not upload confidential, export-controlled, or supplier-restricted CAD data to a public converter. Use CATIA V5 or an offline converter for proprietary engineering files, and check the service’s retention and deletion terms before submitting any business data.

Quality and compatibility limits

Mesh tolerance controls both appearance and dimensional accuracy. Excessive chordal deviation makes curved faces visibly faceted and can change printed dimensions; an unnecessarily fine mesh increases file size, import time, and slicer workload. Choose a tolerance below the manufacturing process’s permitted dimensional error, then measure critical features in the target application or on a test print.

For reliable slicing, the STL should contain a closed, consistently oriented solid. Gaps, self-intersections, inverted normals, zero-thickness faces, and overlapping shells can create missing regions or incorrect toolpaths. CATIA, CAD Exchanger, MeshLab, and many slicers can diagnose or repair some defects, but correcting invalid source geometry in CATIA is preferable.

The export is effectively one-way with respect to design intent: importing the STL back into CATIA produces faceted mesh geometry, not the original sketches, constraints, features, or parametric history. Keep the CATPart as the master file and use the STL for mesh-based manufacturing or exchange.