Week 8 - Challenge 1 - Draft Analysis on a Fan Cover

AIM: To Create the tooling axis for the given Fan cover model meeting the requirements of the draft angle and perform the Draft analysis on the given part model.

Draft:

Draft is an angular tapering given at the design stage to every Plastic Component that has to be manufactured. It is given in the direction of the Mold Movement. The Draft allows the parts to release easily from the mold without creating friction between the surface of component and the core and cavity plates.

When a Plastic component cools down inside the mold, the natural tendency of it is to shrink and attach to the core or cavity half. The movement of mold opening causes friction on the walls of the component as well as the core/cavity blocks. This reduces the life of the mold as well as the component itself. The component may also have rough surface finish as well as weak structure due to this. This problem can be solved by giving draft to the component.

Most applications require minimum draft angles of around 0.5° to 1°, however 3° draft angles are widely accepted for cost saving purpose. 7° Draft angles are given to textured surfaces like Instrument Panels. Minimum possible draft angles are given to screw bosses ribs and stiffeners due to their critical nature.

Draft Analysis:

The Draft Analysis command enables you to detect if the part you drafted will be easily removed from the mould. 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 of angles along a defined draft direction using colour codes. It highlights the regions of draft using colours. . Draft analysis is the first step performed after receiving the Class A of the component.

Tooling Axis:

The direction in which the mold or core and cavity opens is the tooling axis. Part Drafts are designed along this axis.

Class-A Surface:

In automotive design, a class A surface is any of a set of free form surfaces of high efficiency and quality. It is the visible aesthetic surface of any automotive component.

Draft Analysis on Fan Cover :

1) Check the class-A surface :

Check the Class-A surface for any discontinuities in the surface using join operation, boundray operation and disassembly operation.

2)Creating Tooling Axis:

First create a dummy tooling axis as per the given class-A surface. In this case we have chosen Z axis as dummy as it doesn't interfere with any slots or holes.

Create an axis system on the line and point

Using the axis system create the intersection lines along the X and Y directions

Now along the X direction intersection create two lines using point-to-point line command and ctreate a bisecting line using the two lines. Name it as Tooling Axis X direction.

Now same as before create along the Y direction intersection create two lines using point-to-point line command and ctreate a bisecting line using the two lines. Name it as Tooling Axis Y direction.

Now using both X and Y Tooling Axis bisect them create Tooling Axis.

Performing Draft Analysis :

To perform draft analysis change the properties to the material.

Go to insert click on Analysis and select Feature Draft Analysis and move the compass to the Tooling Axis. Change the angle value to 3 degree in the colour scale varient. Click on the surface.

Conclusion :

Green colour indicates the surface having permissible values and Draft analysis status for the fan cover is passed.