Week 8 - Challenge 5 - Core & Cavity Design

Objective:

To perform draft analysis to check if the part has the given draft on its faces. And to determining a tooling axis.

Draft:

It is a tool used in CATIA to make the faces taper with respect to tooling axis. Tooling axis is the direction of mold part ejection.

Why draft is necessary:

A functional part for injection molding has to have draft facing both cavity and core sides to reduce the risk of damage to the parts and ensure ejection. As the molten plastic flows into the closed die and fills the cavity, the material shinks inside the mold upon cooling and as a result grips the core. Without any taper, the part would come out scratched while increasing wear and tear on the mold and shortening the tool life.

Draft Angle Recommendation:

1. 3 degree is nominal draft.

2. 0.5 is minimum draft which increase cost of manufacturing.

3. 7 degree for textured faces.

Steps involved in Draft analysis:

Step1:

Merging of class A surface. All surfaces should be connected no gap should be there we can check it using join command or boundary command if there is gap then green colour line will appear. So we have to make sure the surface is joined.

Step 2:

Now we analyse the best possible tooling direction using the X/Y/Z planes we create dummy tooling line for reference.

Step 3:

Now we create tooling clearance along X/Y direction using the intersection of planes with class A surface.

We intersect Class A surface with XY/YZ/ZX planes and create the reference lines on the surfaces which might face problem during tool ejection. By following similar method tooling direction in X axis.

Bisecting line Concept:

With the help of reference line we make bisecting line which is on the same plane as the reference lines but are in normal direction. They are the either vertical or horizontal lines at the point of intersection of reference line.

Step 4:

Making of tooling direction line. When we get the tooling direction in both X and Y direction then we use bisecting line to generate the tooling axis.

Step 5:

Publish the tooling line and class A surface we publish the output so that it can be used further for making thick body or class B surface.

Step 6:

Draft analysis:

1. We first change the view parameters into customise mode with material checked.

2. Check on insert toolbar then draft analysis icon.

Now draft analysis tool will appear on the screen. It gives information about colour coding mode. Display and direction.

Mode: This option gives details about colour coding and with help of this we can set the parameters of draft analysis also if we want to change the draft angle value for analysis then we can change.

Display option:

1. In this first option is used to hide and show the colour scale.

2. Second option is used for anlysis under point it gives the value of draft with respect to tooling axis selected at given point of the surface. Circles indicating plane tangent to surface.

Direction:

In this we set the compass on tooling direction once the compass is set on tooling axis we lock it so that it does not change. Also we can flip the direction of the tooling if the compass direction is not as per our tooling direction.

DRAFT ANALYSIS OF SWITCH BEZEL COMPONENT:

CORE AND CAVITY DESIGN:

ISOMETRIC VIEW:

FRONT VIEW:

SIDE VIEW:

TOP VIEW:

FEATURES TREE: