CATIA V4

CATIA Requirements

Version 4.2n of CATIA
SurfaceStudio, AutoStudio, Studio or DesignStudio.

Use the following summarized list of modeling practices discussed in this section as a quick reference guide if problems arise.

Before you create the model

Units should be set to mm.

In the Construction Settings window:

The Rational geometry flags should be toggled OFF.

Tolerances should be set as follows:

Curve Fit Distance =.01 mm (lower as necessary)
Curve Fit Checkpoints = 10
Max Gap Distance = .01 mm (this value should remain the same as Curve Fit Distance)
Trim Curve Fit =.005 mm (lower as necessary)

While you create the model

Use degree 5 curves and surfaces to achieve curvature continuity between surfaces.
Models should be transferred periodically from StudioTools to CATIA during construction to manage the quality of the model being created.
Periodically stitch the geometry once it is in CATIA to ensure that the model meets all tolerance requirements.
Avoid using Object Edit > Attach > Attach and Curve edit > Join Curves since these functions create multiknots in StudioTools geometry.
Avoid using Surfaces > Skin between trimmed surface boundaries, since excessive amounts of data are created in the resulting surface. If Skin is used between trim boundaries, the resulting surfaces should be checked for multiknots before export.
Use surface building tools such as Surfaces > Boundary surfaces > Square and Surfaces > Swept surfaces > Rail Surface to ensure and control curvature continuity between surfaces.

Workflow

Before transferring geometry between StudioTools and CATIA, you should consider the purpose of the transfer to plan an appropriate workflow. Two common workflows are:

Geometry (describing mechanical components) is transferred from CATIA to StudioTools as reference data for concept design surfacing, then the StudioTools model is transferred back to CATIA.
A StudioTools model is transferred to CATIA, and both StudioTools and CATIA databases are developed independently. Later, the modified StudioTools model is transferred again to CATIA, replacing the StudioTools geometry from the first transfer. In this scenario, all work done in CATIA on the original StudioTools model (ribs, thickness) will be applied to the new modified StudioTools model.

There are many variations on these two examples. Whatever the transfer scenario, you should carefully plan the transfer process, to ensure that the appropriate data is written out and is useful.

What happens when you replace StudioTools geometry

A common workflow using StudioTools and CATIA together is one where you replace existing StudioTools geometry in a CATIA model file with updated StudioTools geometry. This workflow allows you to continue working in StudioTools, modifying a model that has already been passed over to CATIA.

When you want to update the CATIA database with the completed changes, the surfaces that have been modified are passed to CATIA. You import the new StudioTools geometry and then redefine the skin that includes the faces in question using the Limit2 > Skin > Create/Modify tool.

If you want to make changes to a face or surface using StudioTools and then include that modified surface in the CATIA model, you only have to redefine the skin to its members. That is, this time you leave out the original face and include the new StudioTools-modified face. This way StudioTools geometry can be used to modify CATIA models at any point throughout the development cycle.

What are the curve to fit distance tolerances in StudioTools

The Curve Fit Distance is the tolerance to which trim boundaries are rebuilt to (or approximated). The default positional tolerance in CATIA is .1 mm, and the StudioTools Curve Fit Distance setting should be set to 0.01mm.

This Curve Fit Distance setting should normally be accurate. If you find that it is not resulting in StudioTools geometry that can be successfully used in CATIA, then experiment with the Curve Fit Distance-it can set to as low as 0.005 mm. This setting will enhance the success of post transfer processes, such as skinning, that are to be carried out once the geometry is in CATIA.

Tip Tip

The Curve Fit Distance tolerance in StudioTools should not be set at less than 0.001 mm. Lower than this will impact processing time.

Whether you are creating a model, verifying a model, or debugging a translation, there are a number of tools in StudioTools you can use to check the quality of the geometry you have created. The most useful tool is the Locators > Deviation Min/max measurement tools. Use this tool to check the maximum distance between any two surface boundaries.