Draft Analysis on a Fan Cover

Objective :

• Create the tooling axis for the given Fan cover model.
• To publish the tooling axis and class-A surface.
• Performing draft analysis to verify the creation of the Tooling axis.

Software :

• CATIA V5 (Generative Shape Design)

Introduction:

CATIA V5

CATIA is a multi platform 3D software suite developed by Dassault Systèmes, encompassing CAD, CAM as well as CAE. Dassault is a French engineering giant active in the field of aviation, 3D design, 3D digital mock-ups, and product lifecycle management (PLM) software. CATIA is a solid modeling tool that unites the 3D parametric features with 2D tools and also addresses every design-to-manufacturing process. In addition to creating solid models and assemblies, CATIA also provides generating orthographic, section, auxiliary, isometric, or detailed 2D drawing views. It is also possible to generate model dimensions and create reference dimensions in the drawing views. The bi-directionally associative property of CATIA ensures that the modifications made in the model are reflected in the drawing views and vice-versa.

Generative Shape Design

It provides an extensive set of tools for creating and modifying mechanical surfaces used in the design of complex shapes or hybrid parts. Its feature-based approach offers a productive and intuitive design environment to capture and reuse design methodologies and specifications. Help to design advanced shapes that are based on a combination of wireframe and extensive multiple surfaces. It includes high-level features with full specification capture and reuse.

Draft Analysis

The Draft Analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction at any point corresponds to specified values.

In the molding process the molded parts have to eject from the die so there are some issues while removing the molded parts it may get sticky with the die, or while removing chances to get damaged, so we need to set up is the draft angle this draft angle helps the molded parts to eject from the die easily. the standard of OEM for the plastic components draft angle should be in 3 degrees and if it is sheet metal component 7 degree should be the draft angle, This draft is get analyzed and ensuring the part is with proper draft angles.

OEM Rules for Features Draft Analysis

The truth is no single draft angle can be applied to all part designs. Factors like wall thickness, material selection, ejection, shrink rates, finish/texture, wall depth, and manufacturing capabilities all come into play. But fear not, some simple rules can be followed that can help.

When designing a part, apply as much draft angle as possible a general rule of thumb is 1 degree of draft per 1 inch of cavity depth, but that can change with the aforementioned factors. Try following these general guidelines:

• 0.5 degrees on all vertical faces is strongly advised.
• 1 to 2 degrees works very well in most situations.
• 3 degrees is minimum for a shutoff (metal sliding on metal).
• 3 degrees is required for light texture.
• 5 or more degrees is required for heavy texture.

Draft methodology Flowchart

Features used:

• Line
• Point
• Axis system
• Intersecting
• publication
• Draft analysis

Procedure for finding the Draft axis

1. Check Connectivity to class A surface model.
2. Defining point as Circle point type.
3. Create dummy axis tool at the point as the Z direction.
4. Create Axis System at point 1.
5. Intersect the model with ZX of Axis System 1.
6. Create two point-to-point lines which inclined toward the dummy axis tool.
7. Create Bisecting line with reference of two line and point 1.
8. Edit line color and thickness and assume as X tooling Axis.
9. Intersect the model with YZ of Axis System 1.
10. Create two point-to-point lines which inclined toward the dummy axis tool.
11. Create Bisecting line with reference of two line and point 1.
12. Edit line color and thickness and assume as Y tooling Axis.
13. Create Bisecting line with reference of X tooling axis, Y tooling axis, and point 1 for Main Tooling Axis.
14. Publication Main tooling axis and Class A surface model of Fan Cover.
15. Select View mode and select material as shading.
16. Now select Feature Draft analysis and procedure.

Methodology for finding the Draft axis and Feature Draft Analysis

1. Connectivity Check

First of all, we have to check the continuity of the given class A surface to ensure are class A surface is properly joined or no discontinuity present. This can be done using the join or boundary command in CATIA. By looking visually in the below image we see that surface has a continuously connected boundary as highlighted by the green line.

2. Dummy Tooling Axis

To create a dummy tool axis create a line with points 1 and X-direction.

3. Creation of Tooling Axis

After the surface passes the connectivity check, a tooling axis is created. This tooling axis is used in the draft analysis. It is important to select the right axis for tooling considering the ejection of part from the mold. The next step is to decide the tooling axis direction. The tooling axis is a direction in which mold or core & cavity opens. Analyzing model visually to see which direction is most suitable for tooling axis. From the below image, it is clearly seen that surface has a hole at its top & a cutout at the sides.

4. Finding X Tooling Axis

To find the X tooling axis select intersect option, select the ZX plane of the Axis system as the first element, and fan cover (Class A surface) as the second element. This will give a 2D sketch of fan cover viewing from X-direction.

Now create lines representing the walls of a fan cover using the point-to-point option with the help of intersecting. Using these 2 lines, create the tooling axis clearing X direction. Create a line that bisects these two lines from the reference point in the Z direction. This will form a tooling axis X.

5. Finding Y Tooling Axis

To find the Y tooling axis select intersect option, select the YZ plane of the Axis system as the first element, and fan cover (Class A surface) as the second element. This will give a 2D sketch of fan cover viewing from Y-direction.

Now create lines representing the walls of a fan cover using the point-to-point option with the help of intersecting. Using these 2 lines, create the tooling axis clearing Y direction. Create a line that bisects these two lines from the reference point in the Z direction. This will form a tooling axis Y.

6. Finding main draft tooling axis

To find the main tooling axis create a line using bisecting option and select the 'X' tooling axis as line 1, 'Y' tooling axis as line 2, and Point 1 as a Reference point. Select the bisected line and change color and thickness. this

7. Feature Draft Analysis

• Before performing the draft analysis we create the Main tooling axis then the procedure.
• {Go to menu bar > select insert > Analysis > Feature Draft Analysis} .
• Now, align the compass z-direction with the main tooling axis which we created in the previous steps.
• Now, open the color scale and enter the value as 3 deg.
• Now hover the cursor over the body to check if every face has an angle greater than the given angle.
• Also, if the whole body is in green color it means that the value at all the faces is greater than the provided angle.