What is a .catpart file?

What a CATIA V5 part contains

CATIA is the CAD system of the aerospace and automotive majors, and a CATPart reflects the way those industries work. Inside is the geometry, which is as likely to be a set of precise surfaces as a solid, since CATIA's surfacing tools are the reason many of its users chose it, and the specification tree that built it: sketches, pads and pockets, fillets, and the Generative Shape Design features that produce class-A surfaces. Parameters, formulas and design tables link dimensions to each other and to spreadsheets. Materials, colours, layers and publications, which are named geometry exposed for other parts to reference, round it out.

Units are millimetres throughout CATIA V5, with display settings per user rather than per file, so a CATPart does not have the per-document unit choice that a SolidWorks or Inventor part does.

When another system imports a CATPart, it receives the geometry and none of the tree. Fusion, SolidWorks, Inventor and NX all import CATIA V5 parts that way.

The V5 family, and what is not V5

A part is .CATPart, an assembly is .CATProduct, a drawing is .CATDrawing. The extensions are written in mixed case by CATIA itself, and on Windows case does not matter. A CATProduct holds constraints and references to parts by name; send one without its parts and it opens empty. A .cgr is a lightweight tessellated representation for viewing and clash checking, with no exact geometry in it.

Three generations of CATIA share the name and not the formats. CATIA V4, from the 1990s, used .model files. CATIA V6, now the 3DEXPERIENCE platform, stores designs in a database and exchanges them as 3DXML. "A CATIA file" from an older aerospace archive may be V4, and one from a current OEM may be 3DXML, and neither is a CATPart.

Versions

CATIA V5 releases are numbered R-something, and a part saved in a later release does not open in an earlier one. Suppliers to the aerospace primes have long been required to run the exact release their customer runs for that reason. There is no "save as older release" in the ordinary interface; a STEP export is the answer, and STEP AP203 and AP214 from CATIA are widely trusted because the aerospace supply chain has depended on them for twenty years.

Where these files come from

Aircraft, cars, ships and the components that go into them. Boeing, Airbus and most of the automotive OEMs standardised on CATIA V5, so their suppliers receive CATParts and CATProducts from customer PLM systems. Outside those industries the format is rare, and someone who receives one unexpectedly usually has an aerospace or automotive customer upstream.

Getting geometry out

From CATIA: Save As, and choose STEP, IGES, STL or VRML. STEP AP214 keeps colours and is the export to ask for.

Without CATIA, Autodesk Viewer displays the part in a browser and eDrawings opens it free on Windows. Onshape's free plan imports CATIA V5 parts and exports STEP from the result, which is the free route to something this site opens. Inventor, Creo and NX go both ways on paid licences.

How to open a .catpart file

Autodesk Viewer displays a CATIA V5 part in a browser at no cost, and eDrawings opens one free on Windows. Onshape's free plan imports it. Fusion, SolidWorks, Inventor, Creo and NX import CATIA V5 parts as geometry, all on paid licences. This site cannot read the format.

Editing with the design history needs CATIA V5 itself, or the 3DEXPERIENCE platform that succeeded it. FreeCAD, Blender and Rhino do not read the format at all.

CATIA V5 files are tied to a release; a part saved in a later release will not open in an earlier one, and an assembly is a .CATProduct that references its parts by path, so send the parts with it. CATIA V4 used .model files, and CATIA V6 uses 3DXML, so a "CATIA file" is not always a .CATPart. When in doubt, ask for STEP AP214 or AP242, which every CATIA installation writes.