Free online IGES to OBJ converter

CAD software may require IGES for precise engineering exchange, while Blender, game engines, renderers, and 3D printers commonly require OBJ meshes. Converting the model makes it usable in mesh-based applications, but changes exact CAD surfaces into polygonal geometry.

What the IGES format is

IGES (Initial Graphics Exchange Specification) is a neutral CAD exchange format for transferring engineering geometry between different computer-aided design systems. Files commonly use .igs or .iges and may contain wireframes, curves, trimmed surfaces, and solid-model entities rather than one unified solid.

Mechanical CAD systems such as CATIA, Siemens NX, Creo, Solid Edge, and older AutoCAD releases can create or export IGES files. Engineers and manufacturers use the format for legacy data, supplier exchanges, and transfers between CAD systems that do not share a native file format.

What the OBJ format is

OBJ is a text-based polygon format developed by Wavefront Technologies. It stores vertices, polygon faces, texture coordinates, and optional surface normals. An accompanying .mtl file can define basic materials, while separate image files can provide textures.

OBJ is widely supported by Blender, Autodesk Maya, 3ds Max, game tools, visualization software, and many 3D-printing workflows. It is easier for mesh applications to import than IGES, but it does not preserve parametric features, sketches, constraints, construction history, or exact analytic CAD surfaces.

How to convert the file with FreeCAD

1. Install and open FreeCAD, then choose File → Open and select the .igs or .iges file.
2. Inspect the model tree. IGES imports may contain several faces, shells, solids, or separate objects; select every object that belongs in the exported model.
3. Switch to the Mesh workbench and choose Meshes → Create mesh from shape. Select a meshing method and set the linear or chordal deflection and angular tolerance. Smaller deviations and angles produce a finer mesh, but also create more polygons and a larger file.
4. Select the generated mesh and choose File → Export. Set the filename to something such as model.obj, then select the Wavefront OBJ format if FreeCAD asks for a file type.
5. Open the OBJ in the destination application and check its scale, face orientation, surface smoothness, gaps, and missing components.

For a free conversion without installing software, upload the IGES file to the converter on 101convert.com, choose OBJ, and download the result. Do not upload confidential engineering data unless the service’s handling requirements are acceptable.

Other desktop conversion options

Commercial CAD translators, including CAD Exchanger and comparable desktop applications, can import IGES, tessellate the geometry, and export OBJ. The usual process is File → Open or File → Import, configure tessellation quality, and use File → Export to select OBJ. Menu names and OBJ support vary by product and license, so verify that the installed edition exports polygon meshes rather than only CAD formats.

Quality and compatibility limits

• Tessellation: OBJ contains polygons, not the original exact CAD surfaces. A coarse mesh makes cylinders and curves visibly faceted; an excessively fine mesh increases file size and slows import. Reduce chordal or linear deviation for smoother curved parts.
• Angular tolerance: A smaller permitted angle between adjacent facets improves the appearance of rounded surfaces but can substantially increase polygon count.
• Units: OBJ generally does not carry reliable unit metadata. Confirm whether the IGES source uses millimeters, inches, or another unit, then set the same unit or apply the correct scale when importing the OBJ.
• Invalid source geometry: IGES files can contain gaps, duplicate faces, reversed normals, untrimmed surfaces, or disconnected shells. Repair, sew, or join the geometry in CAD software before meshing when the OBJ has holes or missing faces.
• Materials: Basic colors and material assignments may be written to an .mtl file, but CAD appearance data, procedural materials, and textures may not transfer. Keep the .obj, .mtl, and texture images together when moving the model.
• Editing: The OBJ is a polygon mesh and cannot be edited like a parametric CAD model. Retain the original IGES file as the dimensional master for future feature changes or manufacturing revisions.