Week 8 - Challenge 5 - Door Trim Lower

DOOR TRIM LOWER

AIM: to make a model from the provided class-A surface.
INTRODUCTION:
CLASS-A SURFACE: a surface made by the designer which is given as input to the plastic modeler to work on. It is an aesthetic surface
and the outermost surface.
CLASS-B SURFACE: a surface below a certain thickness from the class-A surface is a class-B surface. This is the surface that contains
engineering aspects of a model.
CLASS-C SURFACE: a surface that joins class-A and class-B surfaces is a class-C surface.
METHODOLOGY:
In this model we have focused on the following things:
Tooling axis
Draft analysis
Class-B surface
Class-C surface
Making a solid model from the surface.
The following tools were used to reach the final step:
Extract
Un-trim
Trim
Extrapolate
Offset
Edge fillet
Boundary
Sweep
Join
Close (part design)
FOR DRAFT ANALYSIS:
First, we analyze the model and then choose a dummy axis in the x and y directions.
As we intersected to proceed we observed that the side walls are not given any draft. Hence we assume the axis normal to the base surface and parallel to the side walls. This surely will create problems because a minimum draft has to be provided.
As the class-A surface is made by other designers only he is authorized to make changes, so we look over this to complete the coin holder for practice.
Now we go to insert< analysis< draft analysis and follow the usual procedure to do the analysis.
Align the compass and click on the surface and as expected the model is mostly in red color i.e. negative draft with respect to the axis.
To correct it as best as we can we moved the compass a bit till we got most of the surfaces in green and lock that position.
After hitting ok, we change the direction of the line from the z-axis to the compass direction. The axis will align itself accordingly.
NOTE: as the side wall does not have a draft, this result was expected and a few areas need correction. But still, we are moving forward to
complete the model

OBJECTIVE: 

To create the Door Trim Lower's Plastic Component using the Class A Surface that is provided. Desired Thickness of the Plastic Component is 2.5mm with 3.2 degrees as the Draft Angle.

First, 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 make the Final Plastic Component and perform Draft Analysis on it as well.

INTRODUCTION:

CLASS A SURFACE:

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 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 surfaces to join them.

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.

By 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. 

TOOLING DIRECTION:

     The Tooling Direction is the direction that the mold pulls apart. The mold is built in two separate pieces,

• A Cavity side and
• The Core side.

The Core pulls apart from the Cavity and that's the Dyeline or the Tooling Direction. The direction in which the mold or core and cavity open is the tooling axis.

FEATURES OF THE TOOL:

CREATING THE MAIN TOOLING AXIS:

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

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. 

CONSTRUCTION OF 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 offset.

 

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 offset 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.

 

To fix all these Patches, we will use the JOIN command in which uncheck the CHECK CONNEXIVITY and in SUB-ELEMENTS TO REMOVE option we will select the filleted surface to remove and click OK. We will do the same for all PATCHES REGION.

  

After removing the filleted surface, we will disassemble the surface body by using the DISASSEMBLE command. Once the 2 surface domain created we will create the BOUNDARY curve for both surfaces.

After creating the boundary curves, we will use EXTRAPOLATE command to extend the surfaces till the intersection then we will use the TRIM command to remove the extra surfaces and they will be joined together automatically.

The same procedure is followed for all REGION PATCHES, and the final result is below with no PATCH REGION.

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:

FINAL SURFACE BODY:

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:

FINAL SOLID BODY:

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.

TREE STRUCTURE:

   

  

ISOMETRIC VIEW:

FRONT VIEW:

SIDE VIEW:

TOP VIEW: