Challenge

Week 8 - Challenge 4 - Coin Holder Design

GGokul Narayanan17 Feb 2022

DESIGN

COIN HOLDER PLASTIC DESIGN

AIM:

To design coin holder from given class-A surface.
Designing class B and class C surface.
Perform draft analysis on the final component.

Procedure:

First, the continuity should be checked in the given Class-A surface. By using the boundary option.

Tooling Axis Creation:

Generally, the tooling axis is created using bisecting line method. But in the components where it has a bin, then the tooling axis is considered as a line normal to the base surface of the bin. The same is done with his component. A line normal to the base surface is created and considered as a tooling axis.

Draft analysis is performed on class A to check the validity of the tooling axis. During draft analysis, it was observed that bin walls are having a 90-degree angle with the base. There is no minimum draft given to walls. Since we are not authorized to make changes in the class A surface, we can inform the class A designer to give the minimum draft to walls.

Draft analysis:

To perform the draft analysis the view parameters are first set to material mode. First, select the axis system and drag the axis system to align and coincide with the tooling axis and lock the orientation. This axis system defines the draft direction according to the tooling axis. Switch on the color scale and set the minimum draft value. Here it is set to 3 degrees and it will be displayed in green color. Any draft angle below 0 degrees will be shown in red color. Now select the running point tool to measure the draft angle at the various locations and then if all surface passes the draft analysis switch on the light effect that will show the component in green color if the component has the required draft angle.

The final draft analysis shows the green color surface having the draft angle above 3 degrees and the red or cyan color shows the draft angle below 0 degrees. All the surfaces with green can be easily manufactured with the injection molding but the red color surface which is a negative draft cannot be ejected or manufactured with the main tooling axis. The solution for this is to have another tooling axis that captures all the rest surfaces but this is not feasible or the last option to make changes in the A-class surface.

Class B surface creation:

As usual, the B surface is created using the standard procedure by extracting, untrim, extrapolating, and offset commands. B surface of this coin holder is divided into base, sidewalls, a top wall, and outer surface. B surface of all these subparts is created and trimmed together to join as a single surface.

The offset distance is kept 2.5mm as component thickness is 2.5mm.

Class C surface creation:

Class C surface for this component is created using sweep command. All the ends of the component surface are facing downwards, So the C surface will be created perpendicular to the B surface.

To create a C surface, the boundary of Class A surfaces adjacent to the boundary is extracted. Then sweep with reference surface command is used and the surface is created at 90 degrees.

Creating final closed volume, converting in the solid body:

Once all surfaces are created class A, class B, and C surfaces are joined together to get the final closed volume. This closed volume is then converted into a solid body using the closed volume command in part design workbench.