Door Trim Lower with Engineering Features

OBJECTIVE:  To create the Door Trim Lower Plastic Component through the given Class-A Surface and then create the Heat Stakes and the Locators considering the design rules for the Door Applique.   

 

REFERENCE IMAGE:

 

MAIN REPORT:

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' which means 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 consist of 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 surface 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.

 

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 are two boundaries present on the Class-A Surface one of which is the Outer-Edge Boundary & the other is the Inner Hole-Boundary. Hence, we can conclude that all the surfaces are well connected. 

 

PROCEDURE TO CREATE THE MAIN TOOLING AXIS:

There are two different methods that we can use to create the Main Tooling Axis for our Class A Surface. When we're trying to create our Main Tooling Axis we always have to focus on the direction in which we're going to create the Main Tooling Axis.

1. Using a Vertex to create a line along the axis which allows us to view all the holes & exposes the maximum surface area of the Class A Surface.
2. Using Inertia Method to find out the Center of Gravity and create a line along it.

 

First, we'll view the Class A Surface from all three axes to determine the most suitable axis along which the Main Tooling Axis can be created.

A) VIEW ALONG THE Z-AXIS:

From the above image, we can observe that not much of the component is exposed from this axis and hence we cannot select this axis as our Main Tooling Axis.

 

B) VIEW ALONG THE X-AXIS:

 

From the above image, we can notice that the case here is similar to the view from the Z-axis as not much area is exposed here and even the hole section is not visible from this direction. Therefore, we cannot consider this axis as our Main Tooling Axis as well.

 

C) VIEW ALONG THE X-AXIS:

From the above image, we can observe that here the maximum amount of the Door Trim Lower's surface area is exposed and we can even view the hole section from this axis hence considering this direction as the direction of our Main Tooling Axis would be the most suitable choice.

 

FIRST METHOD TO CREATE THE MAIN TOOLING AXIS:

Now, to create our Main Tooling Axis using the first method, we'll choose a vertex as shown in the image below to create a line using the 'Line-Definition' command while choosing our Line-Type as 'Point-Direction' where our direction will be towards the X-Axis.

We're not 100% certain that this will be our Main Tooling Axis and to finalize it we have to perform Draft-Analysis and find out if that'll be the appropriate direction. 

 

SECOND METHOD TO CREATE THE MAIN TOOLING AXIS: 

This method may not work for every component but it was considered to be used for this component.

We'll click on the 'Measure Inertia' icon from the 'Measure Toolbar' as shown below:

We'll select our Class A Surface that will open up the 'Measure Inertia' dialogue box as shown below:

After that, we'll click on the 'Create Geometry' option in our Measure Inertia Window that'll open up the 'Creation of Geometry' window. 

There we'll choose 'Non-Associative Geometry' and then click on 'Center of Gravity' to create the required C.G point as shown below:

Now, using the 'Line-Definition' command while choosing our Line-Type as 'Point-Direction' we'll create a line along the X-Axis as shown below:

 

DRAFT ANALYSIS FOR THE CLASS A SURFACE USING THE MAIN TOOLING AXIS FROM THE FIRST METHOD:

Now, We will perform a Draft Analysis on the Class A Surface itself using the Main Tooling Axis created using the First Method:

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'.

It is evident from the above image that the Draft-Analysis on our Class A Surface was successful for the degree of 3 degrees. 

 

 

DRAFT ANALYSIS FOR THE CLASS A SURFACE USING THE MAIN TOOLING AXIS FROM THE SECOND METHOD:

It is evident from the above image that the Draft-Analysis on our Class A Surface was successful for the degree of 3 degrees. 

Hence, we can see that the Draft Analysis was successful along both the Tooling Axes and hence either one of them can be used as our Main-Tooling Axis.

 

PROCEDURE TO CREATE THE CLASS B SURFACE:

We'll start the procedure by creating an offset for the entire Class A Surface at a distance of 2.5mm as that is the desired thickness for our final plastic component.
As this is a complex surface hence the offset will fail to offset every element according to our necessity. It'll select some sub-elements that belong to the filleted regions by themselves that we have to remove to get the rest of the surface that is offsetted.

This warning will be shown when we'll try to offset the Class A Surface.

These 'Sub-Elements' will get selected by themselves to be removed if we want to obtain the rest of the offsetted surface.

In the above image, CATIA is showing us the filleted regions where these sub-elements are located that are going to be removed after the offset operation.

Now, we're going to fix these patches by recreating these sub-elements using various tools such as Extract, Untrim, Extrapolate, Multi-Sections Surface, Trim, etc.

 

1. FIRST REGION:

Here, we're going to use the Class A Surface and extract certain sections of it to recreate the Class B Surface. First, we're going to extract the section of the surface shown below in BROWN COLOR from the Class A Surface, and then we're going to offset it by 2.5mm.

 

After that, we're going to create a boundary using limits and extrapolate along that limited boundary to trim it with other sections later.

 

2. SECOND REGION:

Here, we're extracting the second section from the Class A Surface as shown below:

Then, we're going to offset it by 2.5mm:

Now, we're going to create a boundary using limits in the direction we want to extrapolate this section of surfaces as shown below:

Then, we're going to extrapolate it with respect to the boundary that we have created as shown below:

 

3. THIRD REGION:

Now, we're extracting the third section from the Class A Surface as shown below:

Then, we're going to offset it by 2.5mm:

After that, we'll create two boundaries with limits in purple and yellow colours as shown in the image below:

 Now, we'll extrapolate this surface along those boundaries we created as shown below:

 

4. FOURTH REGION:

 Then, we're going to offset it by 2.5mm:

 

Now, we're going to trim these sections of surfaces with one another but before doing that we'll use the intersection command to check whether it is feasible to trim them together or not.

The intersection between the second and third regions is shown below:

The intersection between the first and third regions is shown below:

 

TRIM OPERATIONS:

First, we'll perform the trim operation between the second and third regions as shown below:

After that, we'll trim the first region with the trimmed surface above as shown below:

Then, we'll join the fourth region with the trimmed surface above as shown below:

Now, the only region that needs to be fixed is shown below:

We're going to fix this by using Multi-Sections Surface to create the missing surface and then join it with this surface as shown below:

 

Then finally, we'll provide the required fillets on the Class B Surface.

 

PROCEDURE TO CREATE THE CLASS C SURFACE:

We'll create the Class C Surface with respect to the Class A Surface and provide draft angles to those surfaces that are parallel to the Main Tooling Axis. Surfaces at the bottom won't be needing any draft angle as they'll get cleared by the core itself. To create the Class C Surface we have to use various commands such as Sweep with Reference Surface and With Draft-Direction depending upon the necessity and at places where it'll be difficult for us to create a surface using Sweep, we'll use Multi-Sections Surface to create those surfaces.

We've to create two Class C Surfaces, one is for the outer surfaces and the other is for the holed region inside the component and both of them are shown below:

A) Outer Class C Surface:

 B) Inner Class C Surface:

 

Now, we're going to Join the Class A Surface with both inner and outer Class C Surfaces as shown below:

After that, we've to trim these joined surfaces with the Class B Surface but before that, we'll create an intersection between these two surfaces and see whether they're feasible to be trimmed with one another. We'll extrapolate those regions where they aren't intersecting and use the intersection command again to inspect whether the intersection is successful or not. When we'll obtain a complete intersection between these two surfaces we'll trim them together to obtain the final closed body as shown below:

To check whether this body is closed or not we'll use the Boundary Command on it as shown below:

From the above image, we can see that the final closed body doesn't have any boundaries, and hence our final closed body is obtained successfully. 

Finally, we'll go to the Part Workbench and use the option 'Closed Surface' from the 'Surface-based Features' toolbar to convert the final trimmed body into a solid body as shown below:

 

After that, we’ll perform a Draft Analysis on the Final Part in Part Workbench:

DRAFT ANALYSIS FOR THE FINAL PART USING THE MAIN TOOLING AXIS:

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 the compass 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.

As this component was made from a trimmed Class A Surface and hence we aren't required to provide a draft angle to every region. We have provided a draft angle of 3.2 degrees to all the required surfaces.

After that, we'll click the surface of the Final Part the results of which are 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

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

 

PROCEDURE TO ADD ENGINEERING FEATURES:

1. LOCATORS

2. HEAT STAKES WITH GUSSETS

 

USE OF LOCATORS: Any workpiece has 12 degrees of freedom for movement in space that consists of 6 Axial and 6 Radial Degrees of Freedom. All 12 degrees of freedom must be restricted to ensure proper referencing of a workpiece. These 6 Axial Degrees of Freedom permit Straight-Line Movement in both directions along the 3-principle axis shown as X, Y & Z. The Radial Degrees of Freedom permit Rotational Movement, in both Clockwise & Counterclockwise radial directions around the same three axes.

 

We have two objectives when assembling the child component with the parent component:
1. Accurately position the part at the desired coordinates.
2. Restrict all degrees of freedom except the one direction in which it'll fix so that the part cannot move.

 

PROCEDURE TO CREATE THE LOCATORS:

We'll create the points at which we are supposed to create the locator using the reference image provided with the challenge as shown below:

We'll create the necessary plane so that we can create a positioned sketch with a projection point for the locator as shown below:

SKETCH FOR THE LOCATOR:

Then, we'll go to the Part Workbench and use the PAD Command to create a Thickened Body with Neutral Fiber as shown below:

1. PAD DEFINITION: 

    

 

2. DRAFT DEFINITION:

   

    

After providing the draft we'll check the wall thickness at the top section as it should be greater than 0.75mm according to the design rules.

 

3. CHAMFER DEFINITION:

 

4. EDGE FILLET DEFINITION:

 

COMPLETE VIEW OF THE LOCATOR:

 

1ST LOCATOR:

 

2ND LOCATOR:

Similarly, we'll build the second locator and assemble them both with our plastic component using via Boolean Operation of Union Trim as shown below:

 

PROCEDURE TO CREATE THE HEAT STAKES:

We'll create Heat Stakes at points as shown below: These points were provided with the challenge for the Heat Stakes.

 

To create a Heat Stake, we'll begin with a Positioned Sketch as shown below:

According to the Design Rules, the Wall thickness of the Heat Stake should be within 60% of the Thickness of the Plastic Component and since the thickness of our Plastic Component is 2.5mm hence 60% of it is 1.5mm.  

1. PAD DEFINITION:

   

 

2. DRAFT DEFINITION:

  

 

 

3. EDGE FILLET DEFINITION:

After creating all the Heat Stakes at the required positions, we'll provide an Edge-Fillet definition of 0.25mm following the Design Rules.

 

We'll limit the height of the Heat Stake to 14mm from the surface on which it is created as shown below:

 

The height of the Locators will be around 20mm so that locators can come in contact with the parent component first and accordingly the heat stakes positions will get located on their own. 

 

PROCEDURE TO CREATE GUSSETS FOR THE HEAT STAKES:

Gussets are Support Features that Reinforce Areas such as Walls or Bosses to the floor. Just as bridge beams and columns are supported at their vertex with gussets to add critical strength to the structure, the same concept applies to plastic injection moulding.

The difference between Ribs and Gussets is that ribs are usually thin wall supports added internally around walls to achieve better geometry and support. Gussets, on the other hand, are thicker wall supports to add strength and reinforcement to existing plastic features.

Recommended Thickness of a Gusset at the Wall is 50% of the Wall Thickness. Typically, the gusset height is less than four times the wall thickness, preferably two times the wall thickness.

 

REQUIRED SKETCH FOR GUSSETS:

 

1. PAD DEFINITION:

 

2. DRAFT DEFINITION:

We'll provide a draft of 0.5 degrees on all the required faces as shown below:

   

 

3. CHAMFER DEFINITION:

 

4. EDGE FILLET DEFINITION:

 

HEAT STAKE WITH GUSSETS:

 

OUR FINAL PLASTIC COMPONENT WITH ALL THE NECESSARY ENGINEERING FEATURES:

 

DRAFT ANALYSIS ON THE ENGINEERING FEATURES:

From the above images, we can see that the required draft angle is met and these features will clear themselves along the Main Tooling Axis for an angle of 0.5 degrees.

 

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:

 

TREE STRUCTURE:

1. CLASS A SURFACE:

 

2. MAIN TOOLING AXIS:

 

3. CLASS B SURFACE:

   

 

4. OUTER CLASS C SURFACE ELEMENTS:

   

   

   

   

   

  

 

 

5. INNER CLASS C SURFACE ELEMENTS:

   

   

 

 

6. EXTRAPOLATE OPERAITONS FOR PROPOER INTERSECTION:

 

7. FINAL JOIN AND TRIM OPERATIONS:

 

8. HEAT STAKES:

A) POINT FOR HEAT STAKES:

 

B) SKETCHES FOR HEAT STAKES:

 

C) SKETCHES FOR GUSSETS:

 

9. LOCATORS:

 

10. FINAL PLASTIC COMPONENT:

 

11. PUBLICATION: