Week 8 - Challenge 3 - Coin Holder Design

COIN HOLDER DESIGN - CHALLENGE 3

AIM

Create the Coin Holder Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the draft angle requirements and performing the draft analysis on the model at the end.

1. INTRODUCTION

A coin holder is a part that acts as a pocket for carrying coins and other small things like pen drives, keys, etc. Mostly is placed in a very easily accessible point where a driver can grab things in the con holder without any difficulties.

CLASS-A Surface

Class-A surface means visible surface. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.

CLASS-B Surface

Class-B surface means the thickness of a part it is not visible and is inside part. In other words, the Class-B surface is a surface below a certain thickness from the class-A surface. This is the surface that contains engineering aspects of a model.

CLASS-C Surface

The surface that joins class-A and class-B surfaces are class-C surfaces. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled

2. OBJECTIVE

• To design coin holders as per automotive industry Standard.
• Create a tooling axis for the given CLASS-A surface.
• Create B Class and C Class
• Create a final surface model and covert it into the solid body using the close surface command in the part design workbench
• Perform draft analysis for both Class-A surface and Final part body.

3. DESIGN METHODOLOGY

Skin data would be provided by the styling team to the part designer

The first step is to check the continuity of the class A surface. This is to ensure that there is no gap between surfaces. If we find any then we should fix that first.

3.1 Class-A continuity check

• Analyse the class A surface through visual inspection.
• To make sure that the given surface has no gap in between them, We can check it also with the help of Join or boundary commands.
• Continuity error has been detected on the top left corner in between the top wall and the side flange area.

Reworking on the error surface

• STEP 1- Join the CLASS-A surface without the error face and its adjacent faces.

• STEP 2- Hide the error face and create the boundary curves with the help of adjacent surfaces. Then the ing sweep command creates a new face with tangent continuity along the support faces.

• STEP 3- Join the sweep surface and adjacent surfaces with the first joined surface and check the continuity and boundary of the joined surface.

Here the reworked surface has only one boundary which means the surface has no patches or irregularities and it is good to go for further design procedures.

3.2 Procedure for creating the tooling axis

The tooling axis represents the opening and closing of the mold core and cavity during the manufacturing of the components. A plastic product designer should consider the best tooling direction to cut down the cost of the component very less.

Method opted for creating tooling axis for the Coin Holder

• Check the best tooling direction for the given surface.
• We can find out the best tooling direction by cross-checking all three axes.
• Since it has a bin with walls, extract the base surface and create a midpoint on it.

• Create a new axis system concerning the point created.
• Here by checking it is clear that the best possible tooling direction is along the z-axis.
• Using intersect command, make intersects along the x and y direction.
• Check the draft angle for the wall faces. All the walls were created with a draft angle of 3.02 degrees. Hence, we can create a line on the point and along the z-direction for creating the Tooling axis.

• Another method for creating the tooling axis is by using the intersection, creating two lines on the walls, and then creating a bisecting line with the two lines on the point.

3.3 Draft analysis for the given CLASS-A surface

The Draft Analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction at any point, corresponds to specified values.

Draft analysis is done after determining the tooling axis, draft analysis is used to check whether the minimum draft (3 degrees) is maintained or not.

The procedure for performing the draft analysis is as follows

• Change the view mode of the component to be in customized parameter mode and then select the shading mode as materials.

• Then open the featured draft analysis tool from the insert menu.

• Then click on the use the compass to define the current drafting direction and then drag and align the compass on the Tooling axis.

• Then lock the draft direction and perform draft analysis by clicking on the component.
• The green color shows the positive daft tooling direction and the given surface passes the draft analysis.

• Click on the analyses under the running point to check the draft analysis on the individual faces. It shows how much draft on specific points when we move the cursor point.

3.4 SURFACE-B CREATION

• the First step is to extract the base surfaces
• Untrim the extracted surfaces
• Extrapolate the untrimmed surfaces
• Trim the extrapolated surfaces and then offset them with a 2.5mm distance along the desired direction

• Extract the side walls and follow the same procedure done for the base surfaces and offset it 2.5mm outwards

• Offset the side walls and Trim them with the base surface

• Then multi-extract the top side walls and extrapolate them. Trim the extrapolated top wall with the side wall surface.

• Extract the side flanges, extrapolate them, offset them, and the trim with the above surface created

The last procedure is to provide desired fillets to the edges of the surfaces in such a way that the final surface should have a uniform thickness. And CLASS-B surface is created.

3.5 SURFACE-C Creation

The method for creating the class-C surface is

• First create the boundary curve of CLASS-A surface using the Boundary command Or Extract command.

• Then multi extract the adjacent surfaces for supporting the sweep surface to be created.

• Using the Sweep command with the reference surface option, sweep the curve at an angle of 90 degrees towards the class-B surface.

• The swept surface created is the CLASS-C surface.

3.6 Creating the Final surface for the coin holder

• Join the CLASS-A surface with the CLASS-C surface.

• Trim the joined surface with the CLASS-B surface to get the final surface

3.7 Go to the part design workbench and using the close surface command create the base bracket solid part body

3D Part model in various orientations (Isometric, Front, Side, and Top View)

The expanded Tree Structure for the geometrical set and the Part Body

4. DRAFT ANALYSIS of the Final part body

The same procedure for the draft analysis of the CLASS-A surface is followed.

• Change the view mode to material shading
• Align the Compass with the Tooling axis.
• Lock the draft direction and perform the Draft analysis.

Conclusion

I have successfully created the class-B and Class-C surfaces of COIN HOLDER using the given Class-A surface along with the tooling axis in the CATIA surface workbench. And also created the final part body using the close surface command in the part design workbench and performed draft analysis for the same