This is question I came across several times. This time I picked it from a forum.

Quote (Edited):

The best method I have found is STEP files.

I use a program called ADOBE 3D Viewer, which directly opens CATPART files, and they can then be exported as a STEP and opened in SolidWorks.

You will find that features such as cylinders will get broken into two half cylinders, making mating to the STEP files difficult (often easier to delete the face and replace with a SolidWorks component).

This user is perfectly right. Typical case of ‘Lost in Translation’ (see  0:12).

The .model contains actually 2 models: one in faceted solid but with links to exact geometry (cones, cylinders) and one purely surface bspline based but with transponant. To make things easier all surfaces are splitted so that periodic cases never occur. To keep up with tolerances, surfaces are actually patches of surfaces so a simple cylinder can be made of up to 36 surfaces. 

The benefit of direct translator is that it will use in the same time the capabilities of source and target system. When using an intermediate file like STEP the translation is blind. Direct translation must be understood as a continuous dialog between original data and target system. To be safe the STEP as to be generated on the least know capability of systems so the result is heavy and vague.

Tolerances: The tolerance available in the CATIA V4 .model file can be used to stitch surfaces. Using STEP you are bound to STEP tolerance model which is weaker than CATIA V4 model and weaker than SolidWorks capability. Guess what you lost information during the transfer.

Surface Type: Using a direct translator both models are used. If the original surface is supported on the target system let’s leverage it. If not it is still time to degrade it to a nurbs. Only if the system don’t support nurbs will we split the surfaces to small patches. A contrario if target system supports cyclic surfaces we will on purpose join the two halves of the cylinders, cones to obtain a single seamless surface.

Attributes. Yes at some stage it count be useful to be able to track original JELE identifiers inside the target model. We are focused on the industrial, heavy-duty market so tracability is part of quality. Keeping track of links with original data is a way to assure that the ‘lost in translation’ can be evaluated.

Comparison: This is another advantage of direct translation. ability to load imported models as near as possible from the original representation and eventually comparing the model as finally built-in the target system allows to confirm the quality of translation. Comparing source with intermediate and again intermediate with solids in kernel solid modellers is way different from comparing original to final using target APIs. 

Size: .model can be very large. 200 megs is common in automotive industry. They can even been grouped via a .session file. Most STEP importers will not accept such volumes.

Now on the benefits of using neutral files I found:

• Long term conservation. Instead of aiming a precise target we keep a neutral file we will be able to load in a future system. This is specially important when doing a project review long after for extracting lessons learned and best practices.
• Exporting to Step is available in CATIA. It’s also available in SolidWorks and free. If sender company was willing to cooperate this would be an easy and cheap solution. This is not common. It would depend also on agreement on the way to use and understand standards.
• We have seen recently some occasions where the translation was done in a different shop. Three parties were involved Sender, Intermediate and recipient of the file.

This is the original article on Engineering tips.