Free online IGS to BREP converter

Source format: igs

IGS or IGES is a widely used CAD exchange format for sharing 2D and 3D geometry between different engineering and design systems. It is common in mechanical design, product development, tooling, and manufacturing workflows where models must move between software packages from different vendors. IGES files often contain surfaces, curves, wireframes, and sometimes limited solid data, making them useful for interoperability rather than for native editing.

Target format: brep

BREP stands for boundary representation. It describes a 3D solid or surface model by defining its faces, edges, and vertices. BREP is valued in CAD and engineering software because it preserves precise geometric boundaries and is well suited for downstream modeling, analysis, CAM, and manufacturing preparation. Compared with exchange formats like IGES, BREP is often better for maintaining a clean, editable solid model inside systems that support it.

How to perform the conversion

The best method depends on the CAD software you have, but the general workflow is the same: import the .igs or .iges file, verify the geometry, then export or save it as .brep.

1. Open your CAD application that supports both IGES import and BREP export. Common choices include FreeCAD, Autodesk Fusion, Rhino, SolidWorks, CATIA, or other professional CAD systems.
2. Use File → Open or File → Import to load the .igs file.
3. Inspect the model for missing faces, gaps, or broken surfaces. IGES files sometimes import as separate surfaces instead of a watertight solid.
4. If needed, repair or stitch the geometry so the model becomes a valid solid or a clean boundary representation.
5. Export the model using File → Export or File → Save As, then choose BREP or a BREP-compatible format supported by your software.
6. Save the output as .brep.

In FreeCAD, for example, you can import the IGES file and then export the resulting shape as BREP if the object is a valid solid or shape. In many CAD tools, the export option may be labeled simply as BREP, Boundary Representation, or a native solid format that stores BREP data.

Notes on quality and limitations

IGES to BREP conversion is not always one-to-one. IGES is an exchange format, while BREP is a geometric model representation, so the result depends heavily on the quality of the source file and the capabilities of the CAD application.

• Surface healing may be required. IGES files often contain unstitched surfaces, small gaps, or inconsistent normals.
• Not every IGES file becomes a valid solid. Some files import only as surfaces or wireframes, which may limit BREP export.
• Precision can vary. Tolerance settings during import and repair can affect edge matching and model integrity.
• Feature history is not preserved. BREP stores geometry, not the original parametric design tree from the source CAD system.
• Software support differs. Some programs can read IGES but cannot export true BREP files directly, so check your CAD tool’s export options first.

If the goal is manufacturing or downstream CAD editing, it is usually best to convert only after confirming that the imported geometry is clean, closed, and suitable for BREP export.