Week 8 - Challenge 4 - Bumper

AIM: Create the Bumper Plastic component through the given Class-A surface.

OBJECTIVE:

• Creation of tooling axis for the given Class-A Surface
• Give proper draft for the surface
• Take the thickness of the component to be 3 mm
• Conduct draft analysis of the model

INTRODUCTION:

In this project, we are designing a bumper plastic component through a given Class-A surface using the Catia software, from that we create a Class-B surface with a thickness of 3 mm throughout the component. And Class C is also created using both Class A & B. Draft analysis is also conducted with a minimum of 3 degrees as standard. Make sure that the surface model is completely closed before converting into solid.

Draft

In engineering, draft is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees or mm/mm (in/in)

• Drafts (or taper) in a mold, facilitate part removal from the mold. The amount of draft angle depends on the depth of the part in the mold, and its required end-use function.
• The draft is in the offset angle in a direction parallel to the mold opening and closing.
• It is best to allow for as much draft as possible for easy release from the mold. The minimum taper angle is 0.5 to 1 degree but 3 degrees is a widely accepted norm.
• The mold parting line can be relocated to split the draft in order to minimize it. If no draft is acceptable due to design considerations, then a side action may be required at a greater expense in tooling.

Draft Analysis

Displays a color gradient on the faces of selected bodies to help evaluate the manufacturability of your design. Select the bodies to evaluate and the axis to define the direction. Use the options to refine the gradient display. In Catia, we use the feature draft analysis tool for this.

Tooling Axis

It is the direction in which the mold or core and cavity open is the tooling axis

Bisector Method: It is a common method used to create a tooling axis for Class-A surface, firstly select the direction in which tooling is difficult there may be one or two directions on a single surface. Then, create an intersecting curve with respect to the surface by taking a plane as a reference and draw lines that coincide with the intersection curve where the draft occurs, then bisect these lines to get the tooling axis. Use this method in another direction if needed. Finally, bisect those axes to get the tooling axis for the surface.

Class-A

Class-A surface given to us

PROCEDURE

Step 1 - Creation of Tooling Axis

On this surface, we are going with the trial and error method by selecting a random point on the surface. For that, I take the center of the hole as my reference point by multi-extracting the boundary of the hole and closing the surface using the fill command and taking the center of the fill surface as a reference, and drawing a line in the x direction.

In this design, the bisector method is more difficult compared to this method.

Step 2 - Draft analysis of Class-A Surface

Draft analysis is conducted with a limiting value of 3 degrees. By this, we confirm whether our trial and error method for selecting the tooling axis is correct or not.

It is showing that all the surfaces are more than 3 degrees. So the tooling axis selected was correct.

Color scale used:

Draft more than 3 degrees shown as green.

Step 3 - Creation of Class-B Surface

In this, the Class-A surface is offset to 3 mm but we may face some gaps occur. To solve that extract the boundaries of the gap and use the fill command to close the gaps. Finally, join all the filled surfaces and offset surface into a single surface using the join command.

Step 4 - Creation of Class-C Surface

Class C Surface is the connection surface of Class-A and B. For this, multi-extract the boundaries and then extend them using the sweep command separately. Join the swept surface into a single one using the join command.

Step 5 - Final Trim:

Class-A + Class-C

In this, we connect both Class-A and C using the join command and make sure there is no gap between A & C.

Class-A + Class-B + Class-C

This made the final output from the surface workbench by trimming all the unnecessary portions and check the surface is completely closed.

Step 6 - Draft Analysis of Final Plastic Component

Color scale used:

Draft more than 3 degrees shown as green. The draft below 0 degrees is shown as blue. Draft between 0 and 3 degrees shown as red.

On the Class-C surface, in some of the portions it is almost clear the minimum draft angle with respect to the tooling axis still shows blue color in draft analysis.

CONCLUSIONS:

• Tooling axis for the given Class-A Surface was created.
• Given proper draft for the surface
• Taken the thickness of the component as 3 mm
• Draft analysis of the model and Class-A are conducted.

1. Isometric View

2. Front View

3. Side View

4. Top View