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 model.

Draft:-

The draft is an angle provided for the part which is going to be manufactured by a molding process,it is just a taper with

some angle on the faces of the part.

This is done for easy removal of parts from the mold and to get a good surface finish.

In this figure,part A has a draft for the cavity part,here it gets damage to the part when detaching due to the shrinkage

of material while detaching and in part b the draft provided on both the inner and outer faces of the part,here it will be

easy to deatch with a good surface finish.

Major industries use the minimum draft angle is 3 degrees.

Procedure:

Detailed report :

1. Checking continuity of given class A surface :

First of all we have to check continuity of given class A surface to ensure class A surface is properly joined or no

discontinuity present.This can be done using join or boundary command in CATIA.By looking visually in below image we

see that surface has continuous boundary as highlighted by green line.

Check the tree directions (X,Y,Z-axis) and finally,we decided which is the best possible direction to produce a mold.That

the draft analysis intially assumes Z-axis direction.

In the Z- axis direction,the faces are either positive or negative draft. So the Z- axis we have taken as a dummy tooling

axis we need to create a perfect tooling axis.

Process:

Tooling axis:

It is defined as the direction in which the mold opens or core and cavity.

Create an axis system on a point.

Create an intersecting line on the ZX-plane and class-A.

Pulling direction: The direction corresponds to the reference from which the draft faces are defined.

Draft angle: This is the angle that faces make with the pulling direction.This angle may be defined for each face.

Paritng element: This plane,face,or surface cuts the part in two and each portion is drafted according to its previously

defined direction.

Neutral element: This element defines a neutral curve on which the drafted face will lie. This element will remain the

same during the draft.The neutral element and parting element may be the same element.

Steps:

1. For checking the gaps present in shape design,use join and noundary options.
2. use the join feature and select the fan cover .If there are any gaps,we will get lines on the model.

3.Use boundary ooption to get lines at boundaries of the fan cover.

Use the fan model for draft analysis.Check the fan cover in all directions(X,Y,Z directions) for all directions.

Since the Z-axis is the best toolong direction,we make a point at the hole center.

Add axis system at Z-axis with a center point.

All dummy tooling axis at the center point.

Add two lines using point to point relation lines at two ends,as shown below.

Add bisecting line for the two lines,as shown below.

We get a center point line at the center of the model.Name it as X-axis tooling axis.

Now make an intersection for the different planes(YZ-Plane)

Draw two lines using point-to-point relation as shown in the figure.

Draw a bisecting line w.r.t to two lines,as shown below.Name its as Y-axis tooling direction.

Draw a bisecting line using the X and Y-axis tooling axis. The below direction axis is the tooling axis and change

graphical properties.

Add material as customization in view mode for draft analysis.

After selecting draft analysis,we get these two dialogue boxes.In the first row,two modes are displayed.

The second row is dispalyed and the third is direction.

Uisng modes,we can use drafting angles at a different minimum and maximum angles.

The dispaly is done using background light and analysis.

In the direction,we use the direction axis and lock it.

Adjust the axis system using the direction 2nd option.After adding an axis,do an analysis at each and every direction on

the model.As shown below,the analysis is done on the fan cover.The below are done when drafting angle is 3 degrees.

At each and every fan cover place,we get the angle,at each posotion.

When we change mode,the analysis is done at the range of draft angles -20 to 20 degrees.

Whenever the red colour is displayed then the drafting is not possible.

Tree structure: