Catia V5 Parameters and Formulas ...

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Catia V5 - Parameters and Formulas Tutorial
Table of Contents
I.
Tutorial Overview
A.
Disclaimer
B.
Software Requirements
C.
About Parameters and Formulas
II.
The Design Process
A.
Pre-defining the Part
B.
Part Layout
C.
Creating Parameters
D.
Assigning Parameters
E.
Creating Formulas With User Defined Parameters
III.
Getting Help
A.
Online Documentation
Other
IV.
Acknowledgements
B.
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I. Tutorial Overview
A. Disclaimer
This document is provided as a free resource, to encourage Catia V5 users in the never-
ending quest for new and better skills. It has been provided at the time and expense of
the author, with no monetary compensation. The author has no desire to control the end-
use of the knowledge received from this document; however, use of any portion of this
document for commercial training purposes is strictly forbidden. This tutorial is to
remain forever in the realm of free knowledge transfer. Please report any misuse or
violation of this free usage policy.
B. Software Requirements
The intended audience of this tutorial, is Dassault Systemes customers using Catia V5,
Release 14 or higher, with a minimum recommended P2 configuration, MD2 license, or
better. The author is using Catia V5 R14 SP09, and HD2 license.
C. About Parameters and Formulas
These topics are beyond basic Part Design. It is assumed that the reader has mastered
basic skills of creating parts in Catia V5. Therefore, no extra attention will be given to
the details of steps leading up to the subject matter. This is necessary for clarity and
brevity.
Having said that, the purpose of creating Parameters and Formulas, is to allow the user a
means to quickly and meaningfully design and edit a part, based on user-defined logic.
But what does that mean? Simply put -
you
, the reader, have the ability to set up
relationships that make editing the part easier, not only for yourself, but downstream
users! By using a little forethought and ingenuity, the designer (and/or other end-user)
can build a part that can be edited on the fly, without ever re-visiting a design function.
This tutorial will explore how to set up parameters and formulas in a methodical way, and
to try to steer the reader away from common and painful mistakes en route to the end
product. In future tutorials, we will explore ways to integrate the knowledge gained here,
into further automation of the design process.
Let’s begin.
TIP:
The screen shots included in this tutorial may be too small to view when
printing. This document is best viewed on the screen, with a zoom ratio of 200%.
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II. The Design Process
The example begins with the selection of a suitable part to be designed. In this case, the
example will be based on an open-ended “box” type part, which could represent either a
machined, or deep drawn process. We will explore the design requirements, and build
the part step by step. It is recommended that the reader follow all steps, and save the
resultant part for future tutorials. As always, save your work often.
A. Pre-defining the Part
At this point, the reader may or may not understand anything about parameters and
formulas. Thus, it would seem a good time to further simplify the definition of
parameters and formulas. Parameters could be thought of as variables and/or constants,
(depending on the use) and formulas are the equations. Used in this context, some of the
“mystery” of parameters and formulas quickly begins to fade.
We will begin by visualizing, or paper sketching the part we wish to create and control.
The design process usually begins with something like this:
From a rudimentary sketch, we will gather all of the information we need to completely
lay out the part. This sketch shows that we have several important characteristics to
control:
1)
Length, width, and height
2)
fillet dimensions (inside and out)
3)
material thickness
We will also give thought to the 3D model, and its downstream application. Part
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numbering also becomes relevant to this design.
To logically determine how to set up relations, we must eliminate redundancy. A good
approach would be to think of how this part is produced. We will assume, for the time
being, that this is a deep drawn part, regardless of thickness. We know that the part has
the 3 basic dimensions of a box – LxWxH – this is a given. And, the part has material
thickness. But there are 4 fillets on this part. By studying the sketch, we can deduce that
2 of these fillets are independent, and 2 are dependent. That is, 2 fillets require a defined
value, and the other 2 are based on the values of the first 2. (those that required input) To
clarify that, the outside fillets are a function of the inside fillets, + the material thickness.
This can be one of our formulas!
After just a brief glance of this sketch, it can be determined that the following values are
candidates for parameters or formulas in our design process:
1)
Part Number (we will discuss this more later)
2)
Length
3)
Height
5)
Material Thickness
6)
Inside Vertical Fillet
7)
Inside Horizontal Fillet
8)
Outside Vertical Fillet
9)
Outside Horizontal Fillet
Before moving on, you may ask yourself, “why add a parameter, when I can just change
a fillet size, or change the dimensions of size in the model?” That’s a really good
question, and here’s the answer: Have you ever opened a model, and had to spend time
hunting through operations to figure out which was which? Or have you ever broken a
model by modifying the wrong feature, resulting in a frustrating, and seemingly never-
ending update cycle? Why not add a parameter, which tells the end-user exactly what
he/she is changing? Why not make it clear, and save time and effort for everyone? This
point may be lost at this time, but in the course of this example, it shall become
abundantly clear.
It is time to begin designing the part.
4
4)
Width
B. Part Layout
Open Catia, and begin with a new CATPart. For now, name the part 1000001.
Start a new sketch, and place it on plane XY. Once inside the new sketch, use the
“Rectangle” tool to create a rectangle. We will constrain it around the sketch axis by
symmetry, (in both directions) and add distance constraints to iso-constrain the part. The
values of the distance constraints are not important at this time.
The result will look like this:
Exit the Sketcher.
NOTE:
From this point on, DO NOT use the “Datum element” feature. This example
requires history on all created components to function properly.
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