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Validating CAD model translations

Validating CAD model translations

Validating CAD model translations

not sure if this is a right place to ask this question but anyway this issue is for catia users.
myself coming from aerospace. we are sending a lot of models to subcontractors for CNC machining.
the complex RTM mould just changed at some areas during catia to step and then step to solidworks translation.
how do you guys verify that translation done well and there are no changes in 3D?

our catia support advised us to ask subcontractor to save solidworks model in stl format so we can compare stl to catia native part prior to machining. we don't have reverse engineering licenses for that.

any help will be really appreciated.


Jenia Ladkov

RE: Validating CAD model translations

You have to compare the two files (native and converted ) and ensure that it is perfect.

RE: Validating CAD model translations

we compare cog, volume, wet area to validate export to another format. You can add Inertia axis directions if you want.
When you give the step file to someone, you provide the metadata info so then can setup a process that will validate the import.

Eric N.
indocti discant et ament meminisse periti

RE: Validating CAD model translations

I work at a Aerospace Machine shop and some of our customers require us to run a translation verification.
This can be done a variety of ways depending on which customer we are working with.
The main way we verify our tools is by basic overlay of parts, but we usually overlay initial provided file with the converted Catia V5 file.
When different colors are applied to the parts, they show up as a checkerboard surface of the two colors when they are exactly the same.

The other option that is required by some of our customer is the use of a translation software that can read in all the different types of files in the industry.
They read these in and then compare the two files based on parameters you provide. When set up correctly, it will then automatically generate a report showing all the mis-matched areas.
I have had very little luck using these programs and the supports from theses companies suck.
The two softwares i have used are Comparevidia and Kubotek.

RE: Validating CAD model translations

I work at an Aerospace Machine Shop and our customers require us to have a documented translation verification process.
We have also had customers that want us to use their verification software, and we had to show them it didn't work, and then show them what we do that does work.
All of our customers have approved our documented translation verification process.

1st off, don't use STL files for verification. An STL file uses triangular areas or facets to represent a solid model surface, so, they will be different from the original model.
An STL file can be output at a very high resolution, and can be very close to original model, but, it will never be exactly the same. And a high resolution STL file is a much bigger file than the original.

Here is our documented process:
8.2 Validation Process
The Validation Process is conducted by the DP Administrator. The CMM Artifact JCE-001 CATIA V5 model is used as the authority dataset. The model has points on all the features to facilitate the validation process.

8.2.1 The 1st step is a back check to the systems themselves. This identifies any system errors or translation settings issues.

CAD: the Artifact model is output as IGES file CAD, then the IGES file CAD is merged back onto the model and analyzed. The features must check with-in .0005 or less.

CAM: the Artifact IGES file is read in, and then output as IGES file CAM. The IGES file CAM is merged back onto the Artifact IGES and analyzed. The features must check with-in .0005 or less.

CMS: the Artifact IGES file is read in, and then points are taken on the features. The points are then output as IGES file CMS. The CMS software doesn’t merge IGES files. The IGES file CMS nominal point data is analyzed to the Artifact IGES nominal point data. The features must check with-in .0005 or less.

8.2.2 The 2nd step is a crosscheck of the systems to each other. This identifies any translation errors.

CAM: the Artifact IGES is read in. The points are analyzed, and then the features are analyzed to the points. The points and features must check with-in .0005 or less.

CMS: the IGES file CAM is merged onto the CATIA model and the nominal points are analyzed. The points must check with-in .0005 or less.

8.2.3 The 3nd step is a day to day process validation. This identifies any translation errors.

A CAM IGES file is output from the CAD Authority Dataset and used to create N/C program(s).

A CMS IGES file is output from the CAD Authority Dataset and used to create CMS program(s). This CMS file is different from the CAM file. The CMS IGES files have only surfaces (no wireframe or points), and, the product is in a local Axis to the design Datum features.

The product is ran on N/C, and then ran on CMM. Any deviations outside of product tolerance are analyzed to find cause of deviations. Secondary checks are performed with in-house standards.

8.3 Validation will be ran and documented on Form DP-F200 at any new system installation and/or current system revision. Any System shown as validated on Form DP-F200 is accepted by QA for use in manufacture and inspection.

Harold G. Morgan
CATIA, QA, CNC & CMM Programmer

RE: Validating CAD model translations

thanks for the answers.
when i get stp file back to catia i can't see any visible changes. but the problem comes from solidworks.
i don't care about simple models but i do care about some complex and crazy surfacing.

i will start with a simple analysis as Eric said. btw what do you mean by wet area?

Harold i won't use stl file. no licensing. thanks a lot for the verification process.
i have to write my own verification process before it's getting to far.

besides of cog and volume i'll ask subcontractors to do some sections at specified locations and create points with specified distance. in this case i'll be able to compare coordinates. this may be done in a minutes using scripting and some software.

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