Best Practices to Working with Large Models in CATIA and 3DCS

Large models keeping you down? Taking you an hour to save your work? 

Try some of these Tips to make your life easier. 

The following list contains some best practices when working with 3DCS V5 and large models.

Starting a new model:

• Run CATDUA V5 on all parts before starting: Running CATDUA V5 can remove ghost links, internal errors, bugs, but can overall reduce the file size of the parts and assemblies and improve the use of using CATIA V5 and modeling with 3DCS.
• Break links FROM parts to parts and files outside of model using “isolate”
• If a CATPart is linked to an external CATPart; right-click on the solid part, highlight over the Object and select Isolate to remove any external links
• Parts can no longer be updated for design changes using CATIA Update (replace component still works)
• Remove unnecessary parts that will not be used in a 3DCS model

Use Enhanced Scenes to create two, or more, model positions. Enhanced Scenes can create numerous amounts of positions for a 3DCS modeler. A few suggested positions can be the nominal positions of the part, or an exploded position.

Do Not Activate Default Shapes On Open: When opening a model, this option will not load the geometry in the graphic window. This will result in quicker load times for larger or multi-part models:

• Go to Tools -> Options -> Infrastructure -> Product Structure -> Product Visualization Tab to activate/deactivate the option
• To load the graphics, the user can select any node in the tree, such as a Part or the entire product or a sub-product

1. Right-click a part or a product
2. Highlight Representation and select Activate Terminal Node

Not very familiar with CADUA V5? Take a look at DCS's T&T on using CADUA V5 in CATIA

Reducing the overall size of the model:

• Work in V5 Cache Mode and put parts in Design mode as required. Reference 3DCS help file on working in Cache Mode.
• Go to Tools -> Options -> Infrastructure -> Product Structure -> Product Visualization tab and click “Do Not Active Default Shapes on Open”. 
• Convert Assemblies to CATParts (“Black Box")

1. In Assembly Design workbench, go to Tools -> Generate CATPart from Product
2. Select the Product in the tree
3. Replace the Product with the new CATPart

Save Often!:

Both CATIA V5 and 3DCS have ways to automatically save during model creation. Follow the directions below to activate, or deactivate.

• Activate/Deactivate Automatic Backup
• Go to Tools -> Options -> General -> General tab
• Activate/Deactivate Automatic save WTX file:
• Go to DCS Preferences -> General tab and find “Auto Back Up (WTX) on Update Model

Watch Memory Usage:

Set CATIA to watch memory, go to Tools -> Options -> General under the General tab. Activate the Memory Warning and set a percentage.

Using CTRL+ALT+DEL (task window), keep an eye on memory usage (“Commit Charge” at bottom). 

Depending on your hardware, Windows version, and software versions, there is a certain number at which CATIA will crash (note: looking at CNEXT process memory usage not as reliable an indicator – overall seems more reliable). 

If a model is very large, you will push this limit.  Save all work, and restart CATIA when you get close to this (ex. On my workstation, I crash about 2.2GB of memory usage.  I “save all” around 1.8 GB and restart CATIA to be safe). If you wait until you get too close to the memory limit before saving, you could crash during the save.  This is the worst possible situation. 

If you’re really close and not sure if you’ll crash during the save, consider the following - you don’t want to overwrite your current model with an incomplete save: 

In Save Management, click “independent save” option, then only select your CATProducts and save them.  All 3DCS data is saved in the products, so this will save your work.  This assumes that you haven’t modified any parts – if you have then you can select them for save too – but the more you save, the more likely a crash.   Propagate to another directory with save management (if the save fails, your original model will be intact).

Recovering a model:

If crashing during model update or initial open

• Run CATDUA V5 on the assembly and parts
• CATIA V5 will mention which parts are causing an issue or errors

Keep an eye out for errors that mention a certain part

While saving, keep an eye on the list of parts

Update Model will indicate that items are missing.  Choose to delete them but do not save the model at any time.  If the Update completes, then you know the problem was not present in the part of the model that was loaded.  Close the model, reopen and try loading other parts of the model.  At some point you may have a repeat of the crash, and you will know that the problem is in the part of the model that was loaded at the time.  Use this procedure to pinpoint the source of the problem.

Looking for more help with large models? Read our post on Cross Sectioning to help with large models in CATIA

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