IGES from CATIA

The way we convert is with STEP files - much better that IGES.

WT

Try using Rhino as a go-between. Import IGES from Catia, SaveAs IGES for SolidWorks.

BTW, in trying to export IGES cavity and core surfaces to a mold maker for CAM tooling we've noticed that the imported geometry can be very squirrelly. Using Rhino seems to take out some extraneous data, leaving pure surfaces which the CAM software (Teksoft) imports without problems. The export options we used from SolidWorks (specifically for Teksoft) SHOULD HAVE left pure surfaces -- and perhaps it did -- but the data in the imported files were very problematic from multiple standpoints. The files seemed to contain duplicate sets of data causing duplicate tool path generation, and sometimes the "duplicate" tool paths weren't actually duplicates (different depths, and no the cavity and core surfaces were not offset) and sometimes they would bring the program to a halt.

Substitute BIG for LARGE to reply directly. 'Sporky'

You can expect some problems with sheet metal type parts from CATIA.

CATIA's modelling kernel has a higher tolerance for error when declaring whether entities are parallel or normal. I have had CATIA translations of part where supposedly parallel surfaces were off by

3E-6 degrees or less. Not much, but enough to cause SW to say they are not parallel.

The source of this error is in the CATIA file itself, not in the translation. I did have this verified by one intrepid CATIA operator who dug deep enough to find this.

CATIA

The Catia IGES translator is based on IBM IGES Format (IIF). When you save a Catia model as an IGES file, it undergoes two translations: Catia=>IIF=>IGES. The IIF=>IGES step is done by the igesp program. This program has two parameters which affect the accuracy of the model and therefore increase the potential that SolidWorks will be able to form a solid out of the data. You can modify these values by editing the file igesinp.data. The 2 parameters which should be changed are:

SIGFIG COEF n SIGFIG CORD n where n is the number of significant digits. The default values are 8 and 6 respectively. The range of values are from 5 to 14. The recommended values are 14 and 14.

COEF indicates the maximum number of significant digits in the IGES file for a real number that is a coefficient of an equation. CORD indicates the maximum number of significant digits in the IGES file for a real number that is a coordinate. By using the maximum values for these parameters, the size of the IGES file can become large, but the potential that SolidWorks will be able to form a solid out of the data is much greater.

That's probably operator error on the Catia side. Don't they have an adjustable tolerance? Some try to correct modeling errors (or speed up the system) by opening them up. Also to make what *look* like good solids ... well, the systems says that they are knit with the open tolerance, right? Same issues on files translated from other systems with lower tolerances or precision ...

I've seen similar things happen in Unigrapihcs. A sheet metal part is unfolded, modified, refolded, and for some reason the faces are no longer parallel or the holes are off normal by a miniscule amount.

In our position, we are not able to prompt the OEM's to fix their files. Most users also don't understand the variable tolerance thing enough to know how it can mess up a model.

Just be aware that it can be an issue, and the source is not just "translati> >

operator