Week 9 - Project 1 - Door Trim Lower with Engineering Features

AIM

Create the Door Trim Lower Plastic component through the given Class-A surface with Heat Stakes and the locators considering the design rules 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.

It is defined as the direction in which the mould/core and cavity open. Selection of the direction of the tooling axis depends on the ease at which components can be easily ejected.

Generally tooling axis is decided from the natural axis of the design, that is, tooling axis is analysed with the x, y and z axis of the system. If the axis doesn’t clear the draft analysis, the next step is to look for the surface in which the drafting axis can be created in such a way that the axis is normal to the surface taken. These are the methods of deciding tooling axis. Bisecting method is the least used method.

BISECTING METHOD: It is a method used to create tooling axis.

Here, I had used axis direction 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 clear 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.

It is an important feature in Catia which helps the user to analyse the draft on various surfaces. The draft analysis toolbar provides two modes for analysis of the draft, first is the quick analysis which basically has three colours (green, red, and blue) for analysing on the other hand other option is the full analysis mode which enables a few more details into the draft and is used in the complex components.

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.

LOCATORS: It is a feature which is used to arrest the degrees of freedom for the components being assembled.

HEAT STAKES: Heat staking also known as thermoplastic staking is the process of joining two dissimilar materials together. In heat staking we use local heating and cooling to raise the temperature of plastic components and allow plastic reforming to be carried out. This reforming can be used in a wide variety of applications.

Advantages of heat stakes are:

1. Simplification of machinery.
2. Reduced cost of machinery.
3. Multiple fastening points.
4. Allows higher density of welds compared to hot air cold form or ultrasonic welding.

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.
• Create engineering features.
• 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 if different surfaces are given as input and ensure no gap is present between any surfaces. Thus, Class A surface is obtained and publish it. Here, the provided surface is completely joined and can be taken as class A surface.
• For the file provided, there is a projection which is found out to be not the part of real class A surface, so that surface is splitted from main class A surface.
• Publish class A surface.

Creation Of Tooling Axis

• Tooling axis here created is by selecting one of the natural axes as it clears the draft.
• Here, tooling axis is created by extracting one of the surfaces for creating a point and a new axis is created at that point.
• So, a flat face is extracted and created a point at its centre. Axis is also created at that point.
• Now, line is created using line tool and giving line type as point-direction and selected the point and direction for creating tooling axis. Tooling axis is created along y direction.
• Publish Tooling axis.

Draft Analysis Of Class A surface

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

Surfaces obtained are all green in color, which means that the surfaces are clearing the draft analysis.

Creation Of Class B Surface

• Now, Class B surface has to be created. For this, multiple extract is used to extract surface in a single operation. Surfaces obtained are the offsetted for 2.5mm.
• Small filleted portions are avoided from extract and other surfaces are extracted. Small fillets are avoided as when they are offsetted to 2.5mm, fillets cannot be automatically formed in CATIA.
• Similarly, other surfaces are extracted avoiding the fillets and offsetted, extrapolated and trimmed with the main surface to get proper B class surface.
• 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.
• Publish class B surface.

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. Using sweep command, class C surface is created.
• Appropriate sweep is the provided considering the flash and considering manufacturing procedures. Surfaces are extrapolated if necessary.
• Publish class C surface.

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

Class A Surfaces obtained are all green in color, which means that the surfaces are clearing the draft analysis. The faces that are obtained in red will be clearing in core side, as the draft direction is reversed, those red faces will be turned to green which means those surfaces are also clearing draft analysis.

Creation Of Heat Stakes

• Sketch for heat stakes is drawn and it is padded.
• Proper drafts are given for the clearing of the surfaces.
• Fillets are also provided.

Heat stakes are created and it is copied and pasted on part body. It is then transferred using point to point option to the desired position.

Creation Of Locators

• Sketch for the locators is created using position sketch.
• It is then padded and drafts are provided.
• Proper chamfer and fillets are given to the locators.

Creation Of Ribs

• Sketch for the rib is drawn and it is padded.
• The padded ribs are given the proper draft and fillet.

Ribs are created and it is copied and pasted on part body. It is then transferred usig coordinate option to the desired position.

Creation Of Doghouse

• Doghouse are created by following the design rules.
• For this, a sketch is created and a rib is drawn.
• It is the padded by inserting a new body.
• Drafts are given for the surfaces as per design rules.
• For coring, surface is offsetted and it is split from the main surface.

Here a dog house is created and it is copied and pasted on another body. It is then transferred using point to point option and it is placed in the desired place.

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.

Side core has to be created for the doghouse to get ejected. So, a side core axis is also created for checking the draft analysis of the component.

Doghouse clearing with main tooling axis:

Minimum of 1.5-degree draft is provided and the B side engineering features are analysed. Green colour is obtained in the draft analysis, which indicates that the draft provided all are in correct direction.

Minimum of 0.5-degree draft is provided and the B side engineering features are analysed using the side core axis. Green colour is obtained in the draft analysis, which indicates that the draft provided all are in correct direction.

Screenshots Of The Solid Model

CONCLUSION

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

REMARK: I'm using the latest version of CATIA, so I had reviewed the challenge before submitting.