Week 8 - Challenge 5 - Core & Cavity Design

CORE AND CAVITY DESIGN OF A SWITCH BEZEL

AIM:

To Create the Switch Bezel Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the requirements of the draft angle and also Create the Class B Surface & Class C Surface. At the end perform to give thickness of the model and also Create the Core and cavity blocks for the switch bezel designed in the earlier.

DRAFT ANALYSIS

• Draft analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction at any point, corresponds to specified values. Draft is required on all parts in the direction of mold movement in order to allow parts to release or eject from the properly.
• Draft is the angle in which the parts is tapered to allow it to release. As the part cools, it tends to want to shrink to the core side of the mold. The draft allows the parts to release easily from the mold without creating friction between the surface of component and the core and cavity plates.
• Most applications require minimum draft angle of around 5^o to 1^o, however 3^o draft angles are widely accepted for cost saving purpose. 7^o draft angles are given to textured surface like instrument panels. Minimum possible draft angles are given to screw bosses, ribs and stiffeners due to their critical nature.

PROCEDURE:

About Project:

• Here the class A surface of the door switch bezel was provided as in OEMs. I created a class B & class C surfaces from the class A. Then I created a solid body of 2.5 mm uniform thickness using class A, class B & class C surfaces. Finally I successfully performed the draft analysis of the component and creation of core and cavity block of the given components. The steps I followed for the creation of this component are given below.

CLASS A SURFACE > TOOLING AXIS > DRAFT ANALYSIS OF CLASS A SURFACE > CLASS B SURFACE > CLASS SURFACE > CLOSE SURFACE > DRAFT ANALYSIS OF SOLID FEATURE > CORE & CAVITY DESIGN >PARTING SURFACE > CORE DESIGN > CAVITY DESIGN > PARTING LINE.

1. CLASS A SURFACE:

In automotive design, a class A surface is any of a set of freeform surfaces of high efficiency and quality. Class A surfacing is done using computer-aided industrial design applications. Class A surface modelers are also called "digital sculptors" in the industry. Industrial designers develop their design styling through the A-Surface, the physical surface the end user can feel, touch, see etc.

Design check on Class A Surface:

• After reciving class a for the SWITCH BEZEL check for the connectivity of the surface on it. If there is any disconnectivity, use join operation, multiple extract, multi section surface, boundary operation and disassemble.

Join operation:

• Go to join command to join the disconnectivity of the surfaces. Give merging distance =0.003mm.

• When there not connected, after reciving Class A surface, delete only the checking command of boundary operation and disassemble, When there are connected delete join operation, boundary operation and disassemble after the check. The check is over if any disconnectivity do not arise.

2. TOOLING AXIS:

• It is the dirction in which the mold open or core & cavity open. Part drafts are given along this axis.

Tooling operation:

• To deside the tooling axis, the component should be completely clearing the Tooling axis in the given specific direction. Analysis the components, the fan cover components has two walls.
• First one visually check. We can check, which one is possible to Tooling Direction. We can check al x, y & z direcion. If you have hole, what it will happen, you haven separate side core for specific hole. In this draft analysis of fan cover Z – direction is the possible of Tooling direction.

• Create bisecting line for the extended line along the center point on both the line and name it as Tooling Axis.

• Publish it using INSERT – PUBLICATION – Select the Class A Surface & Tooling Axis.
• To make sure that easily visual to work on draft.

3. DRAFT ANALYSIS:

• Change view mode

Customize view parameters.

• Choose the material in shading option.
• Use draft analysis option for class A surface and Tooling Axis.
• Go to INSERT – ANALYSIS – FEATURE DRAFT ANALYSIS.

Commands are to be used during Draft Analysis operation:

• The Draft Analysisdialog box is displayed. It gives information on the display (color scale), the draft direction and the direction values.
• The Draft Analysis.2dialog box showing the colour scale and identifying the maximum and minimum values for the analysis is displayed too.

Mode operation:

• The mode option lets you choose between a quick and a full analysis mode. These two modes are completely independent.
• The default mode is the quick mode. It simplifies the analysis in that it displays only three colour ranges.
• Double-click on the value in the colour scale to display the Value Edition dialog box.
• Enter a new value (negative values are allowed) to redefine the colour scale, or use the slider to position the distance value within the allowed range, and click OK.

Display Mode:

• Uncheck the Colour Scale checkbox to hide the Draft Analysis.2 dialog box, this dialog box only appears in edition mode.
• Activate the On the fly checkbox and move the pointer over the surface. This option enables you to perform a local analysis.
• Arrows are displayed under the pointer, identifying the normal to the surface at the pointer location (green arrow), the draft direction (red arrow), and the tangent (blue arrow). As you move the pointer over the surface, the display is dynamically updated. Furthermore, circlesare displayed indicating the plane tangent to the surface at this point.
• The On the fly analysis can only be performed on the elements of the current part.
• Click the No Highlight Representations button to set the display option of highlight effect sources as "on/off". When checked "On" the surfaces are selected but they will not be seen in the specification tree.
• Click the Light Effect button and the colours of the analysed elements react to the light source.
• Click the Inverse button to automatically reverse the draft direction.
• Click the Compass icon to define the new current draft direction.
• Click the Locked direction icon and select a direction (a line, a plane or planar face which normal is used), or use the compass manipulators, when available.

• Once you have finished analysing the surface, click OK in the Draft Analysis dialog box.

4. CLASS B SURFACE:

• To the value of the thickness of the component to get B Surface. It is a surface it gives thickness from Class A Surface, all the engineering features like screw bar,ribs and other supporting features could be form on the B Surface. In other tream Class B Surface know as Engineering Surface.

Surface operation:

• To create the thickness of the class A surface along with the following steps.
• To create the bezel rest surface area, followed by below figure.

• To create the walls of the switch bezel.
• To be followed by below figure.

• Create the base of bezel surface.

• To trim the base and trim.2 surface.

• To give the correct fillet values to avoide sharp edges.

• Below figure is know as Class B surface.

5. CLASS C SURFACE:

• The purpose of Class C surface is to connect Class A surfaces & Class B surfaces.
• It gives thickness of the model.

Surface operation:

• To help of sweep command it create some thickness of profile.

• To trim the unwanted surface of class C surface.

• To trim the Class B surface & trim.9

• The below figure is know as Class C surface.

6. CLOSE SURFACE:

• Close surface is alos known as thickness of the model.
• Go to part modeling & click the close surface option it create complete model of surface.
• Give the thickness of switch bezel is 2.5mm .

• Draft analysis of the thicken switch bezel model.

• Below figure is know as draft analysis of the switch bezel.

7. CORE AND CAVITY DESIGN:

• The mold core & cavity are the shaped sections in either half of the mould tool which give the plastic product its final shape.
• The hot molten material is injection into the core & cavity and then sets hard into shape. The design of the core & cavity is essential in the correct formation of the product. The sequence of events during the injection mold of a plastic part is called the injection molding cycle.
• The cycle begins when the mold closes, followed by the injection of the polymer into the mold cavity.
• A core is usually made of the best quality sand and is placed into the desired position in the mold cavity. Core prints are added to both sides of the pattern to create impressions that allow the core to be supported and held at both ends.

i. Parting Surface:

• The parting surface of a mold are those surface of both mold plates adjacent to the impressions which butt together to form a seal and prevent tne loss of plastic material from the impression.

• Create the boundary line fropm Class A surface and it Extrapolate up to 10mm.

• Trim the both command Extrapolate and Trim.8 from under Class B surface.

• Trim the class B surface and previous trim.11 command, to get parting surface of core and cavity design.

• The below figure is known as Parting Surface of the core and cavity design.

ii. Core Design:

• The core design is started extracting the parting surface thst becomes the datum for the core and cavity. The parting surface in most of the cases is kept at the b class surface to avoid close and tight contact between the core and cavity.

• Draw Rectangular profile on Axis system XY plane.
• Extrude the profile along Z direction.
• Trim the surface of parting surface with component area and Extrude.
• Fill the top of the surface area.
• To join the Fill surface and Trim Surface to get Core Design surface model.

• To intersect the Axis System of ZX plane and select the core surface model, to get sketch profile.

iii. Cavity Design:

• The cavity is the part where the injector and filling of the molten plastic happens. The cavity block is prepared by first extruding the outer boundary along the tooling direction.

• Draw Rectangular profile on Axis system XY plane.
• Extrude the profile along Z direction.
• Trim the surface of class B surface and Extrude.
• Fill the top of the surface area.
• To join the Fill surface and Trim Surface to get Cavity Design surface model.

• To intersect the Axis System of ZX plane and select the cavity surface model, to get sketch profile.

• The below figure is known as core and cavity sketch profile.

iv. Parting Line:

• A parting line, in industrial casting of molds, is the borderline in which draft angles change direction. That is, it is the dividing line that splits the core and cavity halves of a molded part. It is sometimes a starting point for the mold parting surface.

• To intersect class B surface and Join.7 under class A & C geometrical sets.
• The below figure consider the YELLOW Dotted line is know as Parting line.

v. Solid Body:

• The below figure is known as solid body of Core and Cavity Design.

8. CORE AND CAVITY DESIGN:

• The below figure is final out put of Core and Cavity design.

9. TREE STRUCTURE:

10. CORE AND CAVITY DESIGN OF SWITCH BEZEL.

RARE VIEW:

FRONT VIEW:

TOP VIEW:

SIDE VIEW:

ISOMETRIC VIEW:

CONCLUSION:

• At the end of this model, we can get the complete profile of Switch bezel, also the thickness of the component, Draft Analysis and core and cavity design.