CATIA V5 Best Practices in Part Design

Slide 2

Objective

To achieve easy understandability and comprehensibility of the design

process

To have sufficiently good quality and error free CAD models

Enable easy changes and lower update times

Ensure continuity and security in the design process

Slide 3

Part Design – CATPart

Rule 1

Avoid using hybrid design

• Working in hybrid design environment means that you can create wire frame and

surface features within the same body

• Non-hybrid models are more flexible from a design/modification standpoint and usable

in all workbenches

This should NOT be

selected

Slide 4


Rule 2

If possible, all parts should be designed as “Solid features” in the Workbench

“Part Design”

• When surfaces have to be created, they have to be integrated in the tree structure in

the solid

• With this, control/modification of the geometry becomes simpler

Slide 5


Rule 3

Part Body should not be renamed

Part Body should have only ONE “Boolean” operation – Add

• The properties of the CATPart (mass, volume etc.) are defined by geometry in the Part

Body

Slide 6


Rule 4

Always rename Bodies and Geometrical Sets appropriate to what they stand for

Do not use special characters in the names. It is recommended to insert a “_”

between the words and not to leave any blank spaces

• It is recommended to rename all important elements in the geometry (e.g. point, plane,

line etc.)

• This will enable easy understanding of the tree and geometry

Slide 7


Rule 5

Draft and Fillet should be positioned as early as possible in the structure tree

Draft should come first and then the Fillet

Slide 8


Rule 6

Do not use the colors red or orange for the geometry. These colors are system

colors

Rule 7

Avoid using Ordered Geometrical Set. Use Geometrical Set with which

management of points, curves, surfaces etc. becomes easier. It is also

possible to transfer the Geometrical Set under a body which becomes

necessary sometimes to avoid “update cycles”

Rule 8

Avoid using commands like “MULTI-PAD”, MULTI-POCKET”, “REMOVE FACE”,

“REPLACE FACE”, “REMOVE LUMP”.

These functions access “implicit elements” which can cause update errors.

Slide 9


Rule 9

Do not use the commands “TRANSLATION”, “ROTATION” in Part Design

Problems

• File size increases

• Not very easy to update

Solution

• Use these commands from the GSD Workbench

Advantages

• No abnormal change in file size

• Easy to update

Slide 10


Rule 10 (Saving Condition of CATPart)

Rule 10.1

The Part Body should always be defined “In Work”

Rule 10.2

Only the result geometry should be in “SHOW” and all the other supporting

geometry should be in “HIDE”. All unnecessary elements should be deleted

and the file size should be as small as possible.

Rule 10.3

The View Projection type is set to “Parallel” and NOT “Perspective”

Slide 11

Part Design – Sketch

Rule 1

Try to always use only “Positioned” Sketches

Advantages –

• The position of the sketch is controllable and “defined”. The sketch position cannot be

moved with the compass

• More stable

• The position of the sketch can be changed using “Change Sketch Support”

Slide 12


Rule 2

Profiles in the Sketch should be defined completely

Use Sketch Analysis and ensure that the profile is “Iso-constrained”

Avoid using infinite lines in the sketch

Slide 13


Rule 3

A sketch should contain only one profile. For multiple profiles, multiple

sketches should be used

Advantages –

• More stable change behavior

• REPLACE for every profile separately and easily possible

Slide 14


Rule 4

Create the profiles in the Sketch as simple as possible

Advantages –

• Easy changes possible (deleting, moving)

• More stable behavior

• Arrangement clear (dimensions, constraints etc.)

Slide 15


Rule 5

Avoid filleting in the Sketch. FILLETS are “features” and should appear in the

structure tree

Advantages –

• REORDER of fillets possible

• Easy to modify

• More stable behavior

Slide 16


Rule 6

Sketches should not contain “implicit” elements

• The user should project the reference manually in the Sketch, section it with the sketch

plane or offset the sketch as required. Do not use the geometry reference as it is

Advantages –

• REPLACE of such elements is easier

• Even for hidden reference elements, the reference is visible in the tree as well as in the

geometry

The Sketch Analysis option shows these “implicit dependencies”.

Slide 17


Rule 7

Avoid using the command “Infinite Line” in the Workbench Sketcher

• Even for the “infinite lines”, two end points are created

• These end points can cause problems when “Fit in all” is used

• The Sketch also always remains “Under Constrained”

Slide 18


Rule 8

Never use the same Sketch multiple times, instead define a “Master Sketch”

A “Master Sketch” is placed high up in the structure tree normally under a

Geometrical Set.

An “associative” copy of this “Master Sketch” is used multiple times wherever

required

Master Sketch

Associative Copy, “Copy as Result with Link”

Slide 19


Rule 8 (Continued)..

Advantages of “Master Sketch” –

• The structure is well organized and easy to understand

• Changes to the Sketch are only possible and necessary to the original

• If the “associative copy” is deleted, the original is retained

• “Change Sketch Support” is also possible independently for the “associative copies”

• REPLACE of the “associative copy” does not affect the original

• If the original is deleted, the “associative copy” gets isolated

Slide 20

Part Design – Geometry position

Recommendation 1 - Position point and planes

Do not use the default planes (XY, YZ, ZX planes). Instead create a reference

point (preferably “Zero point” at (0,0,0)) and create new planes in place of the

default planes

The default planes should be put in HIDE and all the further geometry should be

positioned with respect to these new planes (Ref_XY, Ref_YZ, Ref_ZX) and the

new position point (Ref_point)

The new position point and planes should be put in a new Geometrical Set

“Control Geometry”

The default planes put in HIDE

New position point (Zero

point) and new reference

planes created in place of

default planes

This position point and planes

are used for further geometry

creation

Slide 21


Recommendation 1 - Position point and planes

Advantages –

• Easy and stable

• The complete geometry position can be controlled with a single point

• Translation of geometry in space is very easy

• Sketch planes can be easily changed

• Positioning in the assembly becomes simple

Disadvantages –

• Rotation of geometry is difficult

Slide 22


Recommendation 2 – Axis System

This can be used but the following rules have to be followed:

Rule a)

Only a “Right handed Axis System” and Axis System type – “Standard” is to be

used

Advantages –

• Sub structures can be replaced or copied easily (no mirroring by accident)

• Safety in the design process (all analyses are interpreted correctly)

Slide 23


Rule b)

The origin point should always be an “explicit” 3D point

No positioning of the axis with the contextual menu (using right mouse button

click)

Advantages –

• Only with an explicit 3D point, associativity with the subsequent elements (e.g.

sketches) is possible

Slide 24


Rule c)

The rotation of the Axis system should be done from the Generative Shape

Design (GSD) Workbench

Rotation of the axis system with the help of context menu (right mouse button

click) is not permitted

Slide 25


Rule d)

For every Sketch, the origin and orientation with

respect to the Axis system has to be defined

When working with Axis System, only “Positioned”

sketches to be used

Only with complete definition (as shown), the

Sketches are fully associative to the Axis System

Rule e)

New 3D points have to be “explicitly” related to the

Axis system for associativity

Slide 26


Recommendation 2 – Axis System

Advantages –

• Use of full V5 functionality

• Geometry can be positioned anywhere in space

• Modifications, iterations can be realized easily and fast

• Very good performance

Disadvantages –

• The use should be done with caution as per the rules mentioned in the previous slides

• Inability to follow the rules can lead to erroneous results

Slide 27

Part Design – CATProduct

Positioning Possibilities in an assembly CATProduct

Positioning Procedures Advantages Disadvantages

1. Assembly Positioning

All CATParts have an identical origin

(e.g. at vehicle position)

•Components easy to

replace

•No Constraints

•Easy Data Transfer

•Problematic positioning

•Reuse of this part is not

directly possible

2. Relative Positioning

Positioning constraints

between the parts

•Easy positioning

because of associative

assembly position

•Complicated replacement

by updating the

constraints

•Reference elements

necessary

(e.g. contact surfaces)

3. Zero-point Positioning

Positioning constraints between

a part and a reference point

•Free positioning in

space (independent

from other parts)

•Good reusability of the

CATParts

•Complicated creation of

the Constraints (6

degrees of freedom have

to be determined)

Which of the procedures to be used depends on the Project. A combination of

all the three procedures can also be used

Slide 28

Part Design – CATProduct

Rule 1

CATProducts with assembly constraints contain at least one fixed component

Rule 2

In the fix constraint, the option “Fix in space” should not be deactivated

Slide 29

Part Design – Quality Assurance

Quality of the CAD Data

Rule 1

All V5 files should be cleaned with the utility CATDUA V5

Call File – Desk. Select the file that has to be cleaned. Context menu (mouse

third button click) and select CATDUA V5. Push clean in the box, run and

subsequently no errors should be detected

Slide 30

Part Design – Quality Assurance

Rule 2

Use the following “Analysis” tools regularly to control the quality of data during

the design process

Sketch Analysis – (Workbench Sketcher/Tools):

• To analyze the problems within a Sketch

Parameterization Analysis – (Workbench Part Design, GSD/Tools):

• To find out deactivated elements

Replace – (Contextual menu, mouse right button click):

• To detect “implicit” elements

Documents

CATIA V5 Best Practices in Part Design