Challenge 3 - Door Trim Lower with Engineering Features

OBJECTIVE: To create an attachment feature like Locators and Heat stakes on a plastic door trim component 3D Solid CATpart in CATIA from the given Class-A surface by meeting the requirements of the draft angle and the attachment feature guidelines.

MAIN PROJECT:
A) Door Trim Plastic Design:

Given: Class-A Surface
Class-A surfaces refer to high-quality surfaces on a product or tooling that are critical for achieving a flawless and aesthetically pleasing finish. This surface emerges from the creative strokes of freehand sketchers by visualizing the essence of conceptual ideas. The precisely refined sketch is subsequently digitalized, and seamlessly transformed into a sophisticated 3D surface through the utilization of specialized software such as Alias.

High-Level Tree-Structure of 3D CATPart:

Tooling Axis:
The term tooling axis refers to the primary direction along which a mould moves during the manufacturing process. This is particularly crucial in processes such as injection moulding, where the molten plastic material is injected into a mould cavity to form a finished product.

Tooling Axis Creation:

STEP-1: Create a "Constructions" Geometrical Set and construct a point on the Class-A Surface. Draw a line along the y-axis direction and consider it as a dummy tooling axis.

Class-A Surface Draft Analysis:
Before generating the part model, conducting a Class-A Surface draft analysis is important to check the manufacturing complexity and to ensure and understand the potential challenges.

Drafting possibilities based on various axes.
X-axis: Not possible to produce.
Y-axis: Cheap and easy way to produce the component.
Z-axis: Not possible to produce.

The dummy tooling axis passed the 3-deg draft angle criteria for manufacturing the door trim component. Let's consider it as the primary tooling axis and publish it for easy reference.

Class B Surface:
Class-B surfaces are interior surfaces of the part body and it does not require the same level of visual perfection as Class-A surfaces. While Class-A surfaces are primarily concerned with flawless appearance and are typically used for visible exterior parts of a product, Class-B surfaces are utilized for areas where visual perfection is not as critical as it may also contain B-side features like ribs, screw bosses and dog houses.

Class-B Surface Creation:

STEP-1: Create a "Class-B Surface" Geometrical Set and offset the Class-A Surface by 2.5 mm inwards.

STEP-2: Take a boundary on the offset surface to know where the surfaces are missed to generate on offset operation.

STEP-3: As some surfaces are missing on the fillet section, use the Multiple Extract command to extract the offset surface from one edge (shown in green colour) and separate the remaining half surface into sub-surfaces with the help of the Join and Disassemble command.

STEP-4: The surface between sub-surfaces 1 and 2 is generated using the Blend command. The blended surface portion is highlighted in yellow colour.

STEP-5: The same STEP-4 is followed to join the surface with the sub-surface 3 and join them with the initial extracted surface to form a complete surface. Then publish it, so that it will be easy to view for future reference.

Class C Surface:
Class-C surfaces are primarily functional and may have fewer aesthetic requirements compared to Class-A Surface. These surfaces are often used in areas of a product where appearance is not a significant concern, and the primary focus is on meeting functional and manufacturing requirements.

Class-C Surface Creation:

STEP-1: Create a "Class-C Surface" Geometrical Set and take boundaries with limits one by one on Class-A Surface as shown in the below image. Then generate a surface using the sweep command across each boundary with a 3-deg draft angle along the tooling axis as draft direction.

STEP-2: Again take boundaries with limits one by one on the Class-A Surface as shown in the below image. Then generate a surface using the sweep command across each boundary with a 90-deg draft angle with reference to the surface. The generated surface direction should be towards the Class-B Surface.

NOTE: The draft angle is determined based on the surface with respect to the tooling axis:
a) If the surface seems perpendicular to the tooling axis, then proceed with at least a 3-deg draft angle.
b) If the surface seems parallel to the tooling axis, then proceed with a 90-deg draft angle with respect to the surface.

STEP-3: Extrapolate each connecting edge of the generated Class-C Surface up to a certain mm so that the surfaces intersect each other. Then Trim them to form a single surface and publish it, so that it will be easy to view for future reference.

Part Body Creation:

STEP-1: Join the Clas-A and Class-C surfaces and trim them with the Class-B Surface. If it fails at trim operation, take an intersection between conjoined Class-A and Class-C surface with the Class- B Surface and check on the non-intersection area, then extrapolate the Class-B Surface at the non-intersection edges and repeat the same until the Closed surface formation.

STEP-2: Finally, the Door Handle Plastic component 3D Solid is created by the Close Surface command.

B) Attachment Feature Creation:
Heat Stakes Feature:

STEP-1: Create a "Heat Stakes" Geometrical Set and create a plane with reference to the ZX plane on Point 1 and draw the below-shown sketches using Positioned Sketch.

STEP-2: Insert two bodies and pad each sketch at an appropriate length and provide a 0.5 deg draft angle at all faces with tooling axis as pulling direction.

STEP-3: Then trim the bodies using boolean operations to form a heat stake and provide the fillets.

STEP-4: Create the required number of heat stakes by duplicating them and positioning them at the required places.

Locator Feature:

STEP-1: Create a "Locator" Geometrical Set and construct a midpoint between the heat stakes. Then generate a plane and draw the below-shown sketch using Positioned Sketch.

STEP-2: Insert a body and pad the sketch with a thickness of 1.3mm at an appropriate length and provide a 0.5 deg draft angle at all faces with tooling axis as pulling direction.

STEP-3: Then provide the chamfer and fillets to form the 4-way locators.

STEP-4: Create the required number of locators by duplicating them and positioning them at the required places.

Part-Body Draft Analysis:

Draft analysis on the solid part resulted in green and blue regions.

1) The green region states that the part is toolable or produceable by the molding machine and the draft angle is 0.5 deg for the dog house.
2) The blue colour region in the part is shown as the tolling axis direction is opposite to the surface, which is not an issue.
3) The red colour which is not there, in this case, states that the draft angle is less than 3 degrees and cannot be produced in a normal quality moulding machine even though if produced it will result in faulty.

Various Views of Door Trim

Isometric View:

Front View:

Side View:

Top View:

Conclusion:
Thus, the Door Trim Plastic 3D component is created with the attachment features in Catia software by following the design guidelines and standards.