Challenge

Week 9 - Challenge 2 - Switch Bezel Design

SSwapnil Patil21 Jul 2023

A REPORT ON (CHALLENGE) SWITCH BEZEL DESIGN

OBJECTIVE

The objective of the project is to design the switch bezel and to do a draft analysis for it by creating the required tooling direction with the help of Bisecting method.

INTRODUCTION

The control panel bezel is the frame part of the window switch that holds its switch covers and buttons into place. Moulding is the method used to manufacture the plastic trims of an automotive by most OEM’s, hence by considering the manufacturing consideration the switch bezel is designed.

DESIGN CONSIDERATION

Class – A surface should be aesthetically smooth and good.

Class – B surface should have all the supporting features like ribs.

Parting Line should coincide with the B surface since flashing couldn’t affect the aesthetic of Class – A.

Class – C surface should also pass the draft analysis.

PROCEDURE FOR CREATING THE SWITCH BEZEL

First, the given styling surface is checked for any irregularities and if found any then it is corrected by using Trim, Extrapolate, Split and Join commands.

The below image shows that the Class – A surface is clean and no irregularities present, so let's move on to the next step.

Creation of tooling Direction

Considering the Ejection from the cavity of the mould after manufacturing the interior trim (switch bezel) must have the nominal 3-degree draft angle.

Hence the tooling direction is created by considering the above factor and bisecting method is used.

The base surface of the class – A was extracted and a point at the centre is created and an axis system was inserted to the point with the current feature is disabled. Then, using project intersection along yz plane is created and the two inclined lines were drawn inside the positioned sketch.

Then bisecting lines with the two inclined lines were drawn. Now the same procedure is done along the xz plane but on one side we don’t have inclined lines so the centre point is used to extrude a line along the z-direction and gave a measurement of 6 degrees (Tentatively). With these two lines from sketches 1 and 2, the bisecting line is crated and published as Tooling Axis(tooling direction).

Creation of Class B surface

For creating the class-B surface the required surface except the offset surface have been extracted and then untrimmed all the surface. Then all the surfaces have been extrapolated to get intersections between them.

Since the thickness of the Switch bezel is 2.5mm the B-Surface was offset to 2.5 mm and the required trim operations must be carried out.

Finally, the required corners have been filleted to 12.5mm (15mm-2.5mm). [ 15mm - fillet value of the A-surface, 2.5mm – Thickness of the component ]

Creation of Class C surface

The required outer edges of the A-Surface were extracted using Multiple Extract. Then for avoiding the patches the curve is smoothened using the Curve Smooth option. Then by using the sweep command the surface was created with the following feature controls,

Profile type – Line

Subtype – With Draft Direction

Guide Curve – Smooth Curve

Draft Direction – Tooling Axis

Draft Computation Mode – Square

Angle – 3 Degree

Angle Sector – Positive Downward (1)

Length – 20mm

Then by using extrapolate command the edges were intersected between the surface corners which eases the trimming operation.

Now the required portion of the C – surface were trimmed out.

Creation of Close Surface

Now the class – A and Class- C surfaces were joined together by removing the gaps in-between them with the help of extrapolation(tangent continuity) and Trim surface. Then the exact surface of the Switch bezel was trimmed from the above-resulted trim surface with the class-B surface.

Then, by defining the part body by using the Closed Surface command in Part Design, the component's solid body is created.

DRAFT ANALYSIS

Introduction

When a plastic component is made, we can observe that there is a draft angle given on each side from the base which is lesser than 90 degrees. This is because in the criteria of making a plastic material the mold should release the material when finished. if the mold surfaces are 90 degrees the material won't release from the mold because of friction due to contraction of material when cooled.

To resolve this problem we CAD engineers maintain a standard rule to design the plastic mold or die's in such a way that there is no problem while ejecting the plastic component. So a minimum of 3 - 10 degrees of draft angle is given to every plastic component while designing.