What Should Beginners Know About Part Workbench?

This article will take you through the beginner level of working with Part Workbench. Before you dive into the topic, let’s get an overview of Part Workbench.

What’s Part Workbench?

The OpenCASCADE Technology (OCCT) kernel, a professional-grade CAD system with sophisticated 3D geometry creation and manipulation, serves as the foundation for FreeCAD's solid modelling capabilities.  Part Workbench is a layer that sits on top of the OCCT libraries, the Workbench Part.svg. It allows the user access to OCCT geometric primitives and functions. These functions supplied by the Part Workbench serve as the foundation for essentially all 2D and 3D drawing features in every workbench (Workbench Draft.svg Draft, Workbench Sketcher.svg Sketcher, Workbench PartDesign.svg PartDesign, etc.). As a result, the Part Workbench is regarded as the essential part of FreeCAD's modelling capabilities.

What Should Beginners Know About Part Workbench?

 1. MULTI-PAD WON’T WORK FOR INTERSECTION SKETCH

People who come from a Solidworks background are often faced with a situation where they want to do the multiple padding for a sketch and will not get the required result. This is because multipad in CATIA is quite different from what we do for Solidworks

Here, if the sketch has these kinds of intersections and we are trying with multi-pad, we won't be able to pad it properly.

Multipad will work in the following situation where we are not padding an intersection sketch.

2. STIFFENER FOR CIRCULAR BODY.

A normal line sketch won't work as a stiffener for models with circular walls. You may need to modify it a bit.

Let's take the following example.

When we try to apply a stiffener command onto the line, it shows the operation as a topological error.

So, the reason here is that, since the wall is circular, there is only a point of contact between the stiffener and the circular wall. When the imaginary thickness is formed, it is not having further contact with the circular wall.

So to resolve, this we need some editing on the sketch used for the stiffener. Here we just need to extend two endpoints of the line horizontally in the opposite direction with a random value.

Now stiffeners can be performed without any error.

3. HYBRID ENVIRONMENT

Note:- This topic should be coming after learning tree arrangement and surface. But you need to practice your part workbench challenges by disabling hybrid design. 

When you open a new workbench, CATIA will ask for a set of options to enable, before opening the workbench. It includes hybrid design, creating a geometrical set and creating an ordered geometrical set. If you select “create a geometrical set, " you will get a default geometrical set near the part body.

Let's discuss hybrid design in detail.

Enabling Hybrid Design

Method 1

Let's enable hybrid design by file ->new ->Part and click ok. You will get a New Part where you must choose if you want a hybrid environment.

Method 2

You can also enable a hybrid environment by selecting tools ->option -> Infrastructure -> Part Infrastructure -> Part Document

If you select Enable hybrid design inside part bodies, the surfaces, lines, points, plane etc that actually should come under a wireframe category will go inside a part body.

You may also notice that sketch.1 is not showing below the pad.1. Usually the same sketch will be inside both the geometrical set and the part body operation(pad, pocket, revolve, etc.) if you follow tree arrangement.

When activating a hybrid design environment, here the bodies you create subsequently are identified with green icons in the specification tree.

If a CATPart document already contains solid bodies (bodies that cannot include wireframes like point, plane, line etc) or surfaces), CATIA changes the green body icons to grey.

For that, let's create a body by disabling a hybrid design.

Now we will create a solid pad inside the part body. Remember that this was created by disabling the hybrid design option. So the CATIA won't allow any of the point, plane, line, surface etc, inside the body. We will save this.

When we open back the model, you may notice that colour changes from green to grey(note that this will only work if we are currently opening the model in a hybrid environment. For that you need to create a new workbench by enabling hybrid mode and then choose file->open to open the previously saved CATPart or you need to go to tools ->option -> Infrastructure -> Part Infrastructure -> Part Document ).  Because this grey body represents the bodies that won't allow any wireframe and surface element inside of it even if you are working in a hybrid environment.

Here, even after you define the grey part body(which is not a part of a hybrid environment)  inside a hybrid environment, it wont allow the wireframe that you created to go inside of it.

But if you insert a new body in the hybrid environment, the point created is allowed to move inside that newly created body as it is a part of the hybrid environment.

Disabling Hybrid design

Here you may notice that sketch1 is inside both the geometrical set and part body(pad.1). This can be achieved only if we uncheck the Enable Hybrid Design option.

If we move forward and try to create a point by defining (Define In Work Object) the part body, the point will automatically move towards the Geometrical set. Here when we select point, plane, surface etc, the define in work object will automatically select the geometrical sets instead of the part body.

When you deactivate a hybrid design environment in the catia, they are identified with green icons in the specification tree.

Suppose, if you create a part body in a hybrid environment and then you open it inside a disabled hybrid environment, the previously created part body will have yellow colour.

But if the same body is opened inside a hybrid environment, the colour won't change to yellow because our body is already a hybrid one. It will stay green.

In this course, it is recommended that you should always disable the hybrid design.