Week 8 - Challenge 2 - 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– Class ‘A’ surfaces are primarily used in the automotive environment and refer to those surfaces which are visible in a product. In other words: A - class surfaces are those aesthetic/free-form surfaces, which are visible to us (interior/exterior), and have an optimal aesthetic shape and high surface quality.

  Here, one should understand the difference between the internal or external and visible or hidden surface. The surfaces or regions which are visible nowadays are considered for Class-A modelling. It is one of the reasons why the importance of Class-A modelling is increasing day by day. Majority of the time this term is used in Plastic Part designs.

• Class B– The Class B finish is a quality finish with only minimal imperfections. A Class B finish is the most common finish for exterior surfaces. It is normally specified on surfaces such as external covers, panels, and parts that are fairly prominent.

• Class C – The Class C finish allows more imperfections than Class A or B. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled, or surfaces which the Customer feels do not need to meet a high cosmetic finish. This Class is generally used for parts or surfaces which are not viewed after installation or viewed only for service.

MATERIAL: (THERMOSET PLASTIC)

                   A thermosetting plastic is a polymer that irreversibly becomes rigid when heated. Such a material is also known as a thermoset or thermosetting polymer. Initially, the polymer is a liquid or soft solid.

                   Thermosetting polyester resins are used extensively as bonding agents in fiberglass laminations and the like. Polyester resins are less costly than competing epoxy resins. These resins use hardeners to initiate a chemical reaction which leads to curing.

                   On the other hand, polyester can also be used as a thermoset resin with vinyl ester in the production of natural fiber composites in automotive applications such as door panel, seat backs, headliners and dashboards.

FEATURE TREE:-

 PROCEDURE TO CREATING CLASS A SURFACE:-

• 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 Class A surface has some irregularities shown in below figure.So join operation performed on the surface and it became clean surface.
• 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 AXIS:-

• 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.

• To get the radius of fillets the filleted surface is extracted and untrimmed the surface and then the redius is measured.
• 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 ] and  11.5mm (14mm-2.5mm) [ 14mm - 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,
• 

1. Profile type – Line
2. Subtype – With Draft Direction
3. Guide Curve – Smooth Curve
4. Draft Direction – Tooling Axis
5. Draft Computation Mode – Square
6. Angle – 3 Degree
7. Angle Sector – Positive Downward (1)
8. 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 CLOSED 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.

PROCEDURE FOR DRAFT ANALYSIS:-

• First the class – A surface is checked before creating the Class –B&C surface and finally the solid body must be analysed. Both can be done by following the below procedures.
• By changing the view mode to custom view parameters – Material mode then the feature draft analysis is enabled.
• Then the compass was activated and placed with the tooling axis by dragging the red pointer and then locked it.
• Then, by selecting the quick analysis mode, the nominal value will be 3 degrees and checked for the component's draft angle.
• The green colour area shows that it satisfies the 3-degree draft angle. If not satisfied then by using the Running point tool the area is measured and then altered to get a successful draft for the created tooling direction.

 CONCLUSION:-

    Finally the Class – A, B&C surfaces with the Tooling Direction have been Published and the Switch Bezel is moved on to the designing of the next operation – the creation of B-side features.