Anyone who has worked with me, will know that I am not a fan of the IGES file format. Having worked in the Automotive OEM supply chain in the early 2000’s, I have had my fair share of issues with IGES files. Mostly related to geometry that contained missing faces, gaps or faces oriented incorrectly (reversed normals). Having worked in tech support, I cannot express the frustration of clients over the years who have had to “fight” with bad IGES files.

3 Reasons to stop using IGES files:

#1 – IGES is OBSOLETE technology IGES was first published in 1980 and has not been developed since 1996! In fact, not a lot of development has been done to the IGES format since 1994.

#2 – It’s unnecessary

Modern MCAD systems like Autodesk Inventor or Fusion 360 can read in practically any mainstream CAD file format, making IGES files unnecessary. Always try to get hold of the Native CAD data. If the person sharing with you won’t share the original file, see point #3 below. See a list of file formats that Inventor can open here.

#3 – STEP files are better

The STEP format is modern, it was written to replace IGES and conforms to the ISO 10303 Standard. This standard is being actively maintained and improved. STEP is a really robust method of sharing 3D Data between CAD systems.

A bit of IGES History:

IGES was absolutely necessary back in the day. Just like a DXF is to 2D data today, IGES became the standard for sharing 3D data between different CAD systems. But like “Hoover” or “Xerox”, it became the defacto format for all 3D collaboration, and for some reason, years after the superior STEP file, it stuck (in some places) as the preferred file format. The IGES format was developed for the US military with lofty ambitions to make collaboration between different CAD systems a seamless affair. For years it was the only way to share files, and living with geometric anomalies was “part of the job”.

According to Wikipedia:“Since 1988, the DoD has required that all digital product and manufacturing information (PMI) for weapons systems contracts (the engineering drawings, circuit diagrams, etc.) be delivered in electronic form such as IGES format.” This is probably why the IGES standard has remained so prevalent,

A bit of STEP History:

STEP stands for “Standard for the Exchange of Product Model Data”. The development of STEP started in 1984 as a successor of IGES. The IFC file format that is used in Construction, is based on the STEP format.

Translations:

When a CAD system exports out an IGES file, it is translating geometry to an IGES format, this file is then shared and the next CAD system imports this file, and decodes/translates the IGES file into it’s modelling kernel. Essentially every time an IGES file is shared, it is translated twice by 2 different CAD systems, this can introduce inaccuracies. Now think of the geometry we create today, versus when IGES was at it’ts peak, the creators of IGES could never have imagined a generatively designed shape.

Conclusion:

IGES files are an unnecessary dinosaur from the 1980’s. If you value accurate models with less translation issues, start with the native file format, use STEP files if needed, but avoid IGES at all costs.

AnyCAD in Autodesk Inventor makes file translations a thing of the past: