Pantorouter analysis - Point tracing, Sweep volume and Clash analysis

Product engineering and manufacturing has several aspects related to it, and one of which is digital product development. The aim of digital product development is to model the design virtually and conduct all studies related to the design digitally, so that we expend least amount of effort in creating it, in real life and with minimum resources. For example, in case you are designing a piston, you may want to simulate mechanical load conditions, and analyse the maximum stress and keep it under elastic limit of the material.

Depending upon the product that you are modelling, your design requirements may change. For example, before manufacturing an engine, it may be of interest to find if the different parts would clash with each other during the motion. Or you may wish to graph valve position with respect to crank rotation etc. 

Surface toolbar

Surfaces toolbar comprises of tools like Extrude, Revolve, Sphere, Cylinder, Offset, Sweep, Fill, Offset, Blend etc. You can see all of the tools present in the attached picture. There are a few differences with regards to the sketch as we used it in the part-design workbench. 

Surfaces toolbar

If you remember, in the part-design workbench we read about the conditions that need to be met for a valid sketch. You can read about them here again if you have forgotten. Nonetheless, the condition i.e. sketch should not be open does not apply in surfacing and you can use a closed as well as open sketch for making a surface.

College projects for mechanical engineering students

As part of curriculum, engineers need to complete a significant project at a college level which either demonstrates understanding of the topic or solves some existing engineering problem. While there's no dearth of topics for engineering students to explore, however, in my opinion, budget becomes a problem since it may involve buying material to create a project and demonstrate problem solving ability. An alternative to this is using Catia or CAD to demonstrate problem solution or demonstrate problem solving ability. I have listed below four such projects and you can use ideas similar to the ones I have mentioned below.

Using animate constraints to solve simple mechanism problem

The sketcher workbench in Catia, offers a tool known as = Animate constraints. This tool can be used to solve simple problems that may be related to four bar chain mechanism or some other simple mechanism. For example, you can make combination of sketch profiles in 2D, resembling an engine and can animate it.

Using this, you can find out several parameters of interest like if for a certain connecting rod length, crank length etc. will clearance be enough or not. This is ofcourse the simplest example, and you can read more about it here. Another application of the tool can be found here.

Designing parametric gear in Catia

Gears can fundamentally be classified according to the profile of the teeth. The profile of the teeth may be involute, cycloidal, trochoidal or even a combination of these profiles. 

Involute profile in red

The involute profile is basically a path traced by a point on a straight line which rolls without slipping on the circle. The circle is called the base circle of the involute. 

Epicycloid in red

The epicycloid is the path that's traced by a point on the circle as it rotates outside a circle, while hypocycloid is the path traced by a point on the circle as it rotates on the inside of another circle.

Using variable draft & parameters in Catia to model glass-bottle cap

Making parts and assemblies, driven by a set of parameters has always fascinated me. The post is an attempt at showing, how we can leverage a set of a few commands / features and make the part easily modifiable by associating these features with the desired, predefined and well-known parameters. The concept applies to assemblies too. However, for the sake of simplicity, I have used part as an example and not used many features to avoid complication and challenges that may arise with explaining the example itself. So, my main focus is on demonstrating the concept and how you may do such a thing. The example itself, that I have demonstrated may not have any practical utility as such, however the concept itself can of course be applied, and is applied to vast range of problems.

Practise - Animate constraints

If you have practised sketcher long enough, animating constraints should be an easy thing to do. And there are many ways to do this. In this particular exercise, we are basically creating four separate profiles within the same sketch, the DOF (Degree of Freedom) of these profiles is not restricted in anyway and they can move relatively freely with respect to each other at first. Subsequently, the aim is to animate piston profile, crank profile and connecting rod profile movement within a cylinder and case profile. Therefore, they are applied constraints keeping in mind the motion they would undergo. Below you can see the profiles that are created.

Balloon generation, Dimensioning, Dress-up & Annotation

After creating all required views on the drawing sheet, applying dimensions, creating parts and assembly numbers along with relevant annotation, tolerance, machining symbols, welding symbols etc. is the next logical step in creating drawings. We will see how we can apply these. 

Creating balloons

Having an exploded view in drawing along with part numbers in balloons can help parts assembly process. Creating it is also easy, however, you should have the parts positioned in the location in the assembly environment and create that view in drawing. After creating the view, you may want to isolate that view since updating the part / view would disturb the drawing. Before we generate balloons, you may want to modify a few settings using the path Tools > Options > Mechanical design > Drafting > Generation tab and Annotation and Dress-up tabs. 

How to find Catia file version and release information without using Catia?

Catia files are forward compatible i.e. you can save a Catia V5R18 file in Catia V5R19 or above easily without any issues and can prevent the specification tree history. However, it does not offer backward compatibility i.e. files modeled in later release cannot work with prior version perfectly and you will lose specification tree if you open it. Also, you should not save the file else you will also not be able to open it in the release it was modeled and it will be corrupted. 

Title block, Sheets, Bill of materials & Properties

Before we discuss dimensioning and other important aspects of the drawing creation, it makes sense that we talk about other complimentary aspects of the drawing creation. These topics relate to creating title block, adding sheets and modifying properties etc.

Inserting sheet and detail sheet

Sheet

The sheet you are working on, may get full. So, you can either increase the sheet size that you are working in, or you can add additional sheet. We saw how to set drawing sheet, and change projection method and sheet size, if you don't remember, you can see it here. To add a new sheet. you can use the drawing toolbar, or use the path Insert > Drawing > Sheets > New sheet. The new sheet you add will be shown in the specification tree as well as a tab on the top.

Creating drawings in Catia - View toolbar - 2

Remaining tools in the view toolbar can be accessed using the same path i.e. Insert > Views or by using the views toolbar itself.

Creating drawings in Catia - View toolbar - 1

Instead of using wizard to create views, you can also use the Views toolbar. Tools in the view toolbar can also be accessed using the path Insert > Views. Keep in mind, that this toolbar is different from the View toolbar that we have already studied. 

What is the practical application of animate constraints in Catia?

Like many other people, I have played with animate constraints tool present in sketcher workbench, and have had my share of fun in the past. However, today I am going to talk about the way in which this tool can actually be used, so that you become more oriented about its significance and understand one more way in which it can save you some time. One of the most commonly used suspension system in an inexpensive car is MacPherson strut with a control arm and a stabilizer bar and perhaps other one is with a sturt and two control arms, or some other derivative of this. 

Setting drawing sheet and using wizard

These are two ways to create views, if you chose to create an empty sheet while opening the drafting workbench instead of preset views. 

• Using a wizard
• Custom

You may even use a combination of the two, where some of the view may be created using wizard while other using views from the views toolbar. Regardless of the method you choose, as a first step, you should always setup the drawing sheet. In this, you may setup the projection method, sheet size and scale to be used for views. In case you are satisfied with the standard you selected while defining the sheet, you may not do this.

Drafting - Introduction

Engineering drawings are important for many reasons. Before you start to create a drawing, make sure a part or an assembly document is open for which you wish to create a drawing. To create these drawings, there's a specific workbench in Catia that you can use. The workbench is different and is nothing like AutoCAD. You can navigate and open the drafting workbench by using the path Start > Mechanical Design > Drafting.

Opening drafting workbench

Re-use pattern, Sectioning, Save management

We mentioned re-use pattern when we discussed Product structure tools and constraints, however we did not see it practically. Also, there are other concepts worth understanding with regards to an assembly. Let's see them one by one. 

Re-use pattern

Re-use pattern let's us make use of pattern used in part to instantiate and assemble parts easily and quickly. Consider the plate shown below where one of the hole was created originally using hole command, while rest were simply patterned. Now, in an assembly, we are required to put bolts in all holes. To do this, we would only assemble one of the bolt in its place using constraints like offset, coincidence of the axis etc. And that is what is shown below, we assembled one bolt in one of the hole.

One bolt assembled with plate

Creating top-down assembly, Copy and paste, Assembly features

How to create a top-down assembly in Catia?

Making a top-down assembly is same as making a bottom-up assembly, to the extent that you would need to apply the constraints in the same way as you applied during the bottom-up assembly. However, in case of the top-down assembly it is required that we start with an assembly file and make all parts from within that particular assembly file, unlike in case of bottom-up assembly, where we called already modeled parts and assembled them. 

For the top-down assembly, we would create a three part assembly. By creating this assembly in the top-down manner, we would learn how to effectively navigate between product / part environments and modify parts and assemblies from within the single document. The drawings for these parts are present below. We have kept the parts simple for the sake that you can practise easily.

Top-down assembly - Assembly and Parts drawing

Creating bottom-up assembly

To create a bottom-up assembly, you would require already modeled parts saved in a folder. If you have not made the parts or do not wish to make them, you can download the parts using this link. These parts have been made using Catia V5R21, so you can use the same release or higher to work with these parts.

Assembly file, Product1 created

Product structure tools, Constraints, Move toolbar

Creating an assembly requires use of tools that are specific to the Assembly design workbench. Creating bottom-up assembly or even the top-up assembly requires knowledge of these basic tools. These tools are present under Product Structure tools toolbar, Move toolbar and Constraints toolbar. Let's first study these tools and then we will move to creating an assembly. 

Product structure tools

Product structure tools toolbar has the tools for creating new part or product files from within the workbench environment which you may do in a top-down assembly process. It also has tools for bringing in the parts that have been already created for the purpose of assembly. In addition, it also has some other relevant tools.  Below you can see all the tools that are present in this toolbar. Let's see these tools one by one.

Product structure tools toolbar

Practise exercise 2

The exercise below can be made using part design workbench as well as surface design workbench. Modeling the part is quite straightforward. After making the centre hub, you can proceed with modeling blades, which would require you to model it with the use of curves whose details are provided.

Exercise

Practise exercise 1

Below you can see the exercise for practise. The exercise if fairly easy and part can be made in about 30 minutes. This is by no means a part ready for production, since it does not take into account the snap surfaces or draft etc. Nonetheless, it's good for practise since with this exercise, you will come to use many tools that you have studied so far. 

Exercise