Week 8 - Challenge 2 - Switch Bezel Design

AIM

Create the Switch Bezel plastic component through the given Class-A surface and perform Draft analysis.

THEORY

CLASS A SURFACE: Class A surface is a surface made by the designer specially in automotive design which is the aesthetic part of a body and is given as an input to the plastic designer to work on it.

CLASS B SURFACE: It is a surface which comes below the class A surface with a particular thickness. This surface contains engineering features of a model.

CLASS C SURFACE: It is the surface which joins class A with class b surface.

TOOLING AXIS: Tooling axis is the direction in which the core and cavity opens. If we are using proper tooling axis, we can avoid adding side cores thus the cost of manufacturing the component can be reduced.

 

BISECTING METHOD: It is a method used to create tooling axis. Here, the tooling axis is created from other two lines extracted from the class A surface in ZY plane which are inclined and a line is created by selecting bisecting option from the line definition dialogue box. Then another line is created in ZX plane which is given a draft more than 3 degree. Thus, from the above two sketches a bisecting line is created along the point which gives the tooling axis.

Creation of tooling axis using Bisecting method:

Step 1: Rotate the model and finds the surfaces that are inclined and are supposed to affect the tooling axis of a component.

Step 2: By using intersection tool, a curve is obtained from the intersection of the plane we choose and the surface selected. Here, we choose ZY plane and is projected to get two inclined lines for having tooling axis.  

Step 3: Another plane is chosen in switch bezel as there is another inclined plane. So ZX plane is opted and the surface is projected. A line is drawn and is made to have an angle greater than 3 degrees from that.

Step 4: Bisecting line is drawn from the two inclined lines drawn in different sketches, by opting bisecting from line definition. Thus, tooling axis is obtained.

Step 5: From this tooling axis, draft analysis is done to check whether whole surface is clearing or not and thus confirms the tooling axis.

  

Here, I had used Normal to surface as tooling axis as the tooling axis. Because, Bisecting method is rarely used and not proper method of using tooling axis. Using bisecting method to have tooling axis have many limitations. So, while creating a tooling axis, it is recommended to look for the directions in the axis system to have draft analysis. If those axis system doesn’t clears the draft analysis look for normal to surface to have a tooling axis.

DRAFT ANALYSIS: From draft analysis, we can verify draft angles, examine the angle changes within a face, as well as locate parting lines, injection and ejection surfaces in parts.

 

Draft analysis in Catia:

Step 1: Ensure that customize view parameter is enabled and material mode is opted in view mode customization.

Step 2: Now go to insert > analysis > feature draft analysis.

Step 3: Drag axis bar to the tooling direction of part.

Step 4: Check for draft.

 

Surface will be in green if the draft angle is more than 3 degrees, blue if draft angle is between 0 to 3 degree and red if draft angle is less than zero degree.

Three degree is the nominal value for draft, whereas 0.5 degree can also be manufactured at ribs.

OBJECTIVES

• Creation of Tooling axis
• Creation of Class B and Class C surface from provided Class A surface.
• Creation of solid part out of surface modelling.
• Draft analysis of Class A surface and final part.

PROCEDURE

Creation Of Class A Surface

• Class A surface is obtained as the input.  
• Join all the surfaces to obtain Class A surface and ensure no gap is present between any surfaces. Thus, Class A surface is obtained and publish it. 

Creation Of Tooling Axis

• Tooling axis can be created using Bisecting method as explained before.
• Here, tooling axis is created as Normal to surface as it is more acceptable form of selecting a tooling axis. 
• Tooling axis is created from extracting a flat face and creating a point at its centre
• Now, line is created using line tool and giving line type as normal to surface of the extracted surface and create the tooling axis.

Draft Analysis Of Class A surface

• Draft analysis is performed over Class A surface and every surface is obtained as clearing.  

Creation Of Class B Surface

• Now, Class B surface has to be created. For this, flat surfaces of class A surface are extracted. 
• Extracted surfaces are then untrimmed. 
• Untrimmed surfaces are then offsetted to 2.5mm which is the thickness of the part.  
• Now those surfaces are then trimmed to obtain joined and remove unwanted surfaces.  
• Fillets are measured from the Class A surfaces and appropriate fillets are provided for Class B surface by adding or subtracting the thickness of the component to obtain correct thickness everywhere. 

Creation Of Class C Surface

• Now class C surface has to be created and it is created from the boundaries obtained from the Class A surface. This boundary is provided as the input curve for sweep command and tooling axis as the draft direction and with 3-degree draft value.  
• Appropriate sweep is the provided considering the flash and considering manufacturing procedures. Surfaces are extrapolated if necessary. 

Creation Of Closed Surface

• Now Class A surface and Class C surface is joined. 
• Now Class B surface is also trimmed with the obtained surface to get the closed surface. 
• Boundary check is done to check for any open boundaries in the part. 
• The closed surface then obtained moved to part design and close surface tool is used to obtain the part. 

Draft Analysis Of Plastic Component

• The obtained part is draft analysed to check for the correctness of obtained model by following the draft analysis procedure mentioned above.

 

Screenshots Of The Solid Model With The Proper Color Code Of The Draft Angle In Various Orientations

CONCLUSION

• Created Tooling axis
• Created Class B and Class C surface from provided Class A surface.
• Created solid part out of surface modelling.
• Draft analysis of Class A surface and final part is also done.