Switch Bezel Design

Switch Bezel Report:

Aim: To create a Plastic part from a given class A surface of a switch bezel and perform draft analysis on the part.

Objectives:

1. To create a tooling axis for the component.

2. To create Class B & C surfaces form the parameters: Thickness(3mm), minimum draft angle(3°).

3. To create a solid body from the closed surfaces formed by joining and trimming Class A, B & C surfaces.

4. To perform draft analysis of the final plastic component ensuring the minimum draft angle is met on all the surfaces of the part.

Tool Used: CATIA V5.

Introduction: In this project, a Switch Bezel is to be designed using a given class A surface, the parameters for te design are as follows:

• Part thickness: 3mm
• Draft angle: 3°

The part is developed keeping the aforementionedparameters in mind while creating class B & C surfaces.

Constraints:

• Changes if any in class A surface shall be very minimal.
• Part thickness cannot deviate more than 30% of the nominal thickness in any direction.
• All design rules shall be followed strictly.
• All surfaces shall be completely closed before converting to solid. A maximum tolerance of 0.003mm is allowed.

Report:

1. Class A surface:

The following surface is given as the input for the creation of the part. This will be the main aesthetic surface for the switch bezel.

(class A surface)

2. Creation of tooling axis:

• Firstly we visually determine the ideal direction of pull for the simplest geometry of mould, for the given class A surface, the direction of pull should be around the z axis.
• Now, we can extract the base and a origin point and create an axis system to help with the creation of the tooling axis.
• Intersecting the given class A surface in yz plane, an outline sketch is obtained. Bisect the critical lines of the obtained sketch to get tooling direction in yz plane, similarly obtain the tooling direction in zx plane as well keeping the draft angle more than 3°.
• Using the obtained tooling axis, bisect these axis and create main tooling axis, check for the suitability of the tooling axis by visually confirming that all surfaces of class A are visible from the direction normal to main tooling axis.

(tooling axis in yz plane)

(tooling axis in xz plane)

(Main tooling axis created using tooling axis in yz and xz plane)

3. Draft analysis of class A surface:

To continue with the design process first we need to find out the tooling axis for the surface and check for all the drafts using Draft Analysis tool of CATIA. Use the main tooling axis for the draft analysis. The analysis is done for 3° draft, all the surfaces that have more than 3° draft are highlighted in green.

(Class A Draft analysis using main tooling axis)

4. Creation of class B surface:

Class B surface is created by extracting and offsetting the main surfaces of the class A surface. Untrimming, extrapolating and other commands are used to create the outline of the class B surface, The surface is then trimmed and fillets are added as required.

(Class B Surface creation using offset, untrim and extrapolation of class A)

(Class B surface trimmed to obetain outline geometry)

(Fillets added to class B surfaceon the outside; Fillet radius = Fillet in class A- thk.)

5. Creation of class C surface:

Class C surface is created by extracting the boundaries of class A surface and using the sweep command and the direction of draft, surfaces are created, these surfaces can be made smoother by using curve feature. Extrapolate and join the class c surfaces to get a seamless class C surface.

(Class C surface creation using bounadry of class A; Curve used to create seamless class C surface)

6. Creation of a close surface:

• Join the Class A and C surfaces, if there is an open boundary remaining because of the curve smoothening, Class A surface can extrapolated by a tiny amount and trimmed with class C surface.
• After getting a seamless join/ trim of class A & C surface, trim the result with class B surface to get a closed surface ready to be made into a part. Similar to previous, make sure that no open boundary remains so that part body can be formed using the final surface.

(final closed surface using class A, B & C surface)

7. Creation of part using the surface:

Using the close surface feature, make the part out of the created surface.

(Part Body created using Close Surface feature)

8. Draft analysis of Part: Using the tooling axis and similar method to previous, analyse the part for draft angles in all surfaces. Make small changes in angle of draft and angle of pull until all surfaces are shown to have proper minimum values of draft.

(Final Draft analysis of the Part body)

Conclusion: The solid part is obtained using the close A, B & C surfaces. The draft analysis shows the part has proper minimum value of draft on all surfaces. This ensures that the surface finish of the plastic component will be smooth when manufactured with the mentioned draft angle and tooling axis.