Switch Bezel Design

OBJECTIVE: To create the Switch Bezel's Plastic component using the Class A Surface that is provided.

Firstly, we have to create the required Tooling-Axis for the given Class A Surface while meeting the requirements of the necessary Draft Angle & then perform the Draft-Analysis Operation on the Class A Surface itself. 

After that, we have to create the required Class B & Class C Surfaces using which we have to create the Final Plastic Component and perform Draft Analysis on it as well. 

 

MAIN REPORT:

AT CERTAIN PLACES I HAVE WILLINGLY MADE MISTAKES TO EVENTUALLY RECTIFY THEM WHILE EXPLAINING METHODS TO RESOLVE THOSE ISSUES.

Types of Surfaces and their Importance for an Automotive Plastic Designer:

• Class A Surface: Class A is an aesthetic surface with the highest quality finish. Most Class A Surfaces for an Automotive Component are made using 'Autodesk-Alias' based on the final Concept-Sketch. All Class A surfaces should have 'Curvature-Continuity', meaning the continuity between the surfaces should share the same boundary. It is taken as a reference by the Automotive Plastic Designer to create 'Class B' and 'Class C' Surfaces.

 

• Class B Surface: The Class B Surface resides below the Class A Surface at a certain thickness. It is created using Engineering Principles that contain all the necessary features such as Ribs, Bosses, Snaps, etc. This surface isn't visible to the observer from the outside. 

 

• Class C Surface: The Class C Surface is the surface created between the Class A and Class B surfaces to join them with each other.

 

Now, we will begin by checking the State of Connectivity for the Class A Surface and ensure that there are no gaps between the surfaces as all the surfaces should be joined well together with each other and shouldn't consist of any discontinuities between them.

 

Our Class A Surface:

 

 

There are two methods to inspect the State of Connectivity for the Class A Surface:

1. Using the 'Join' Command' from the 'Operations Toolbar': 

First, we'll click on 'Join Command' and select our Class A Surface. Then, we have to ensure that the 'Check Connexity' option is marked as shown in the images below. It will check for any gaps that may be present between our surfaces. Then, we'll click on the 'Preview' button and if it doesn't show any 'Connexity Error' on our surface then it means our surface is well-connected and there are no discontinuities between it.

In our case, there are no 'Connexity Errors' for the given Class A Surface. 

In case there is a 'Connexity Error', we can fix it by increasing the 'Merging-Distance' and then performing a join operation between those surfaces.  

 

2. Using the 'Boundary' Command' from the Operations-Toolbar: 

In this case, we have to click on the 'Boundary' command and then select the Class-A Surface. After that, we'll click on the 'Preview' button to highlight all the boundaries that are on the Class-A surface and check if there are any internal boundaries other than the outer edge boundaries. 

In our case, there is only one boundary present on the Class-A Surface which is the Outer-Edge Boundary and hence we can conclude that all the surfaces are well connected. 

 

PROCEDURE TO CREATE THE MAIN TOOLING AXIS:

To create our Main Tooling Axis, we'll begin by using 'Extract Command' from the 'Operations Toolbar'  & Extract the Base-Surface from the Pocketed-Section of our Class A Surface using 'Propagation Type' as 'No Propagation' as shown in the image below:

Now, we'll create a point over that extracted surface using the point command while defining our 'Point Type' as 'Only Surface'  and then we'll state the Distance as '0mm' that will allow us to create a point right at the middle point of that surface as shown in the images below:

 

Instead of using the 'Default Planes' we will introduce an 'Axis-System' right at that point as shown below:

 

After deploying our new Axis-System, we have to create 'Clearance Lines'  that can be used eventually to create the Main Tooling Axis.

Hence, we are going to start the procedure by creating a 'Positioned-Sketch' along the ZY-Direction taking the point created before as our 'Projection Point'. 

Then, we’re going to create an 'Intersection' using the 'Operations Toolbar present in the 'Sketcher Workbench', and then we're going to use the 'Visualization Toolbar' to go to the 'No 3D Background' mode to work on our Sketch as shown in the image below:

We are doing all this to create a 'Clearance-Line' along the Y-Direction of the Class A Surface.

Now, we'll create two new lines over the lines shown below between these two surfaces so that eventually we can create a mean line between these two opposite surfaces. 

Now, we'll hide all the projected lines and then create a Bisecting-Line using the 'Profile Toolbar' under the 'Line Command'. The Bisecting Line that is created will be longer than we need and therefore we'll make it shorter using the 'Trim Command' as shown below:

After this, we'll convert the lines used to create the Bisecting Line into Construction Elements.

Then, we'll create a Clearance-Line along the X-Axis  for which we're going to create a new sketch.

We'll start by creating a 'Positioned Sketch' along the ZX-Plane using the Projection Point we used for the previous sketch. 

We will use the command 'Cut the Part by Sketch Plane' from the 'Visualization Toolbar' and take an Intersection of the Class A Surface.

 

Then, we'll draw a line on the only surface that we have in the X-direction and since we don't have an Opposite-Surface, we'll draw another line from the center point that will be at an angle of 3-degrees that is required as the our 'Draft-Angle.

 

Finally, we'll have 2 Bisecting-Lines acting as Clearance-Lines along X & Y-Axis as shown below:

 Now, we'll create the 'Main Tooling-Axis' using these 2 clearance lines to create the final Bisecting-Line. 

 

When we view the Main Tooling Axis from the Normal View, we can notice all the Surfaces as shown in the image below and that tells us that the required Draft Angles are present and our Tooling Axis is correct.

 

DRAFT ANALYSIS ON THE CLASS A SURFACE:

Next, We will perform a Draft Analysis on the Class A Surface itself:

Before starting with a Draft Analysis Operation, we will go to the 'Customize View Parameters' option under the 'View Toolbar'. Then we will enter the 'Customize View Mode' where we will go under the 'Mesh' option and select 'Material' and press 'OK'. 

To start the Draft Analysis in the 'Generative Surface Design Workbench', we will go to 'Insert' and then look for the option called 'Analysis'. Once found, we will go under that and click on 'Feature Draft Analysis. This will open the 'Draft Analysis' Dialogue box. There, we will ensure that under 'Mode'  we have selected 'Quick Analysis', under 'Display' we will select 'Show or Hide the Color Scale' and then select '3 Degrees' as the permissible draft angle. Then, under 'Direction' we will choose the icon with the symbol of the compass on it which stands for 'Use the Compass to define the new current draft direction'.

  

From the above results, we can notice that only one surface of the pocketed section has a draft angle that is lower than 3 Degrees.

Using the 'Analysis under the Running-Point' command under 'Display' we can determine the actual angle that is present on that surface with respect to the Main Tooling Axis which is 2.22 Degrees.

 

PROCEDURE TO CREATE THE CLASS B SURFACE:

First, we'll work on the Bezel-Rest Surface for which we will use 'Extract Command' from the 'Operations Toolbar' with 'No Propagation' mode to extract the required surface as shown below:

 

Then, we'll untrim the extracted surface using the 'Untrim Command' under the 'Join Command' to untrim the surface.

 

Now, we'll extract the required walls from the Class A Surface while avoiding all the filleted walls in the Pocketed-Section.

 

Using the Extract command we are going to extract these walls and Untrim them eventually. 

When we unhide the Untrimmed Bezel Rest-Surface, we can notice that not all the walls are properly touching the required surface as shown in the image below:

Hence, we're now going hide all the parents and extrapolate these untrimmed surfaces using 'Extrapolate Command' while defining the 'Continuity-Type' as 'Curvature' & Propagation-Type as 'Point Continuity':

Now, We're going to use the 'Trim Command' to keep the surface that is required and trim other surfaces as shown below:

Now, We need to create the Base Surface similarly.

Now, we're going to offset these walls with respect to the required thickness of the component which is 3mm.

When we're creating the offset, we've to be very conscious of the 'Direction of Offset' as the Class A Surface acts as our limit and we cannot exceed its bounds and create an offset. We have to offset towards the required direction as shown in the image below:

For the walls, Class A Surface acts as the inner limit and hence in this case we will offset it outwards by 3mm.

Finally, we'll offset the Base-Surface:

 

After that, we'll trim them together to create the final Class-B Surface:

 

Results after Trim Operations:

 

APPLYING FILLET TO THE EDGES:

Now, we have to Apply-Fillets to all the required edges but not all fillets' value in the Class A Surface is accurate to be applied on the Class B Surface and hence we have to find a workaround.

We can notice from the below image that the fillet value for the given edge is not accurate as it was trimmed with respect to the Base-Surface and hence the actual edge where the fillet was applied isn't visible. 

We have to extract this filleted surface using the 'Extract Command' and then Untrim it to find the actual geometry using which we'll be able to find out the actual fillet value for this edge. 

From the above image, we can notice the value of the fillet for the edge that was trimmed with respect to the base surface and the actual edge fillet with a value of 15mm.

The value for fillet in case of the upper edges can be seen directly using the measure tool as 14mm.

 

Now, we'll apply these fillet values to our Class B Surface as shown in the images below:

While examining the Wall-Thickness between the Class A & Class B Surface using the Measure Tool we noticed that the wall thickness was uneven which can lead to manufacturing defects such as Flow Lines that can be caused by the varying speed at which the molten plastic flows as it changes direction through the contour and bends inside the mould cavity and especially in case there is uneven wall thickness which is the case here as we can see from the image below:

To fix this, while performing the fillet operation, we have to take thickness of the wall into consideration and subtract it from the value of the fillet to provide enough room for the component to have proper wall thickness.

From the above image, it is evident that the Wall-Thickness is much closer to 3mm now than it was before and hence the desired Wall-Thickness is achieved.  

 

PROCEDURE TO CREATE THE CLASS C SURFACE:

First, we'll create the boundary using the 'Multi-Extract Command' under 'Operations Toolbar' and extract all the required Outer Edge-boundaries as shown in the images below:

(NOTE: We can do this directly using the Boundary Command too but I have chosen to do this with Multi-Extract Command)

Now, as our Boundary Curves are not smooth hence it is needed that we smoothen the curve using the Curve Smooth Command from the Operations Toolbar under the Join Command.

When the Continuity was defined as Threshold in the Curve Smooth Definition:

After changing the Continuity to Curvature in the Curve Smooth Definition:

Then, we'll repeat these steps for the other boundary too and hence the results will be two smooth curves. 

 

After that, we'll use the 'Sweep-Command' with 'Profile Type' as 'Line', The 'Subtype' as 'With Draft-Direction' where we'll select the Guide Curve as one of the Extracted Boundary and choose our Draft-Direction along the Main Tooling Axis, Define the value for our Draft-Angle as 3 degrees and make our Angular Selection along the required direction and create a Sweep Surface

We'll repeat this operation for the other boundary.

 

STEPS TAKEN FOR THE PREVENTION OF FLASHING DEFECTS:

Another thing that we need to notice here is that the Class C Surface is facing outwards onto the B Surface, the Parting-Line will be created onto the B Surface Instead of the Class A Surface, and hence this way it will prevent the chances of Flash-Defect to form on the Class A Surface. Flashing is a moulding defect that occurs when some molten material escapes from the mould cavity. When this extrusion cools down, it remains attached to the finished product and hence if this defect has to occur with the Class A Surface then it'll lose its aesthetic finish and the part will not be acceptable. So, to prevent this from happening, we're placing the parting line onto the Class B Surface.  

 

Also, While inspecting the results after Sweep Operations, we noticed some surfaces needed a better finish as shown below so we ensured that those regions are trimmed and the surface finish was improved.

    

 

FINAL CLASS C SURFACE:

 

Now, we'll Join Class A and Class C Surface with each other using the Join Command as shown below:

After performing the Join Operation, we can notice that some boundaries are existing at inappropriate places and needs to be fixed.

So, to fix this we will enter into the Join Operation again and increase the Merging Distance from 0.001 to 0.003. The limit for increasing the Merging Distance stops at 0.003 as it is the accepted Industry Standard. 

As we can see from the above image the issue remains as the Inner-Edge of the pocketed region is still having a boundary.

To fix this issue we are going to delete the Join Operation and then perform Extrapolate Operation on the Class A Surface.

And now, we’re going to Trim this Extrapolated Surface with the Final Class C Surface as shown in the image below:

 

Hence, the issue is now resolved as there are no inner boundaries present after performing the Trim Operation.

After this, we’re going to trim this surface with respect to the Class B Surface to obtain the Final Surface.

 

 

Now, we'll check the Surface if it is a closed body or not, and to inspect it we are going to use the 'Boundary Command' and try to place a boundary on the body.

From the above image, it is evident that the surface has no boundary and hence it is a Closed Body.

 

Now, we'll move on to the Part-Workbench and create a Solid Body out of it using the 'Closed Surface' Command under the 'Surface-Based Features' Toolbar as shown in the image below:

 

DRAFT ANALYSIS ON THE FINAL BODY:

Finally, we'll perform the Draft Analysis for the Final Part in the Part Workbench:

We'll click on the 'Draft Analysis' under the 'Analysis' Toolbar in the Part Workbench.

Then, we'll click on the Compass Symbol under 'Direction' which stands for 'Use the Compass to define the new current draft direction'.

We'll drag and place the compass on the Main Tooling-Axis.

Then, we'll select 'Show or Hide the Color Scale' under 'Display' and define our Draft-Angle as 3-Degrees. After that, we'll click on the surface of the Final Part to show the results as shown below:

In the Draft-Analysis,

Green Colour stands for regions where the Draft Angle is more than 3 degrees,

Blue Colour stands for regions where the Draft-Angle is between 0-3 degrees, &

Red Colour  stands for regions where the Draft Angle is lower than 0 degrees

 

After inversing the Draft Direction: 

It is evident from the above images that the Draft Analysis is successful and the Final Closed Surface Part is feasible to manufacture. 

Publishing the Main Tooling-Axis, Class A, Class B & Class C Surfaces:

 

Tree Structures:

1. CLASS A SURFACE:

 

2. MAIN TOOLING AXIS:

 

3. BEZEL REST SURFACE FOR CLASS B SURFACE:

 

4. WALLS FOR CLASS B SURFACE:

 

5. BASE FOR CLASS B SURFACE:

 

6. OFFSETS FOR CLASS B SURFACE:

 

7. FILLET VALUES FOR CLASS B SURFACE:

 

8.  FINAL CLASS B SURFACE:

 

 

9. CLASS C SURFACE:

 

10. FINAL TRIMMED SURFACE:

 

PART WORKBENCH AND DRAFT ANALYSIS:

 

3D VIEWS OF THE FINAL PART WITH PROPER COLOR CODE OF THE DRAFT ANGLE IN VARIOUS ORIENTATIONS:

1. FRONT VIEW:

 

2. TOP VIEW:

 

3. ISOMETRIC VIEW: