Week 8 - Challenge 3 - Coin Holder Design

AIM: Create the Coin Holder 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 2.5 mm
• Conduct draft analysis of the model

INTRODUCTION:

In this project, we are designing a coin holder plastic component through a given Class-A surface using the Catia software, from that we create a Class-B surface with a thickness of 2.5 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

Initially extract the base surface from Class-A and create a point center to the surface. Create a line in the z-direction with the surface as a reference. After creating the axis check with the normal view corresponding to that axis and make sure all the draft is visible (as shown below). If so, then take the axis we created as the tooling axis.

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.

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 extracted and then untrim it. Then offset to 2.5 mm and extrapolate all edges along the surface direction. Do this process for each surface separately then trim all the into a single B Surface.

Then give the required fillet. 

Step 4 - Creation of Class-C Surface

Class C Surface is the connection surface of Class-A and B. For this, multi-extract the outer flange and its boundary then extend it using the sweep command (using reference surface).

   

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 is shown as green and below 0 degrees is shown as red.

CONCLUSION:

• Tooling axis for the given Class-A Surface was created.
• Given proper draft for the surface
• Taken the thickness of the component as 2.5 mm
• Draft analysis of the model and Class-A are conducted.

1. Isometric View

2. Front View

3. Side View

4. Top view