Core & Cavity Design of Switch Bezel

OBJECTIVE:

Create the Switch Bezel Plastic component through the given Class-A surface and Core and Cavity designs. To begin with, the tooling axis for the given Class-A Surface is created to meet the requirements of the draft angle and at the end perform the Draft analysis on the model.

The Thickness of the component is Considered as 2.5 mm

INTRODUCTION:

Draft:

• A draft angle is a slant that is applied to each side of most features of an injection molded part. In other words Draft is providing tapers on the product features such as walls ribs posts and bosses that lie parallel to the direction of the release from the mold part ejection
• The nominal draft is 3mm for plastic components and for automotive sheet metal components is 7mm

Tooling axis :

• It is defined as the direction in which the molds opens or core and cavity, with the help of tooling axis created along x and Y axes are used for creating the Main Tooling axis by using the bisecting method

PROCEDURE:

Connectivity of Class A surface:

The first and foremost thing to do is to check for the connectivity of the surfaces this is to ensure that there are no gaps between the surfaces if gaps are present then it should be resolved.

This can be done visually or by creating boundaries, if their gaps are present they are graphically represented by green lines. If not while performing boundary command it shows an error.

Creation of Dummy axis :

This is a normal line which we construct by analyzing the best possible direction(X/Y/Z axis) for the draft for the part, this axis is only for reference and is not used for Tooling Axis

Creation of Tooling Axis for Class A surface:

Taking the dummy axis as a reference, intersect the class A surface along the different axis (XY/YZ/ZX ) Check for the possible places where the part might face difficulties while ejecting the component from the mold.

Lines are drawn at the places where the part boundary has difficulties

Later the Tooling axis in one direction (let’s say X) is obtained by bisecting the lines drawn in the above process

In the same way, the other axis is also checked and then the Tooling axis in another direction(let’s say Y) is drawn

Now both Tooling axes are bisected and the final Tooling direction is obtained which is further used for all draft analysis axis and later unto developing Class C and Class B surfaces

Publication:

The publication is used for easy access to published components. These will come in handy while modeling (we are not required to search the entire tree structure for a particular operation)

DRAFT ANALYSIS:

Click the Inset—Analysis -- (Feature) Draft Analysis icon

If material is not on There will be a warning message is shown and then we need to select the material

The Draft Analysis dialog box is displayed. It gives information on the display (color scale), the draft direction and the direction values

DEVELOPMENT OF CLASS B SURFACE:

Class B surface is created by extracting each wall and untrimmed walls extrapolating the walls and then trimming the extra surfaces and offsetting it to certain value based upon the thickness of the component where it is 2.5 mm. The offset surface will be the B-Surface

DEVELOPMENT OF CLASS C SURFACE :

This surface is obtained by sweeping the boundaries of the Class A surface along the Tooling Axis direction, it connects A and B surfaces

Using B and C surfaces a closed surface is formed by trimming the extra surfaces

The Final trim part is converted into a solid component using closed surface command

DRAFT ANALYSIS OF SOLID PART:

Click the Inset—Analysis -- (Feature) Draft Analysis icon

If material is not on There will be a warning message is shown and then we need to select the material

The Draft Analysis dialog box is displayed. It gives information on the display (color scale), the draft direction and the direction values

Click the Compass icon to define the new current draft direction.

The compass lets you define the pulling direction that will be used from removing the part.

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

DRAFT ANALYSIS COLORS:

Red - < 0 degree

Green - > 3 degree

Blue - 0-3 degree

CORE AND CAVITY DESIGN:

• The Core is the male part which forms the internal shape of the molding. The cavity is the female part that forms the external shape of the molding.
• The core is the side of the tool where the plastic part is injected from; also known as the bottom half of the tool. The upper half of the mold is called CORE.
• The design of core and cavity is essential in the correct formation of the product. The sequence of events during the injection mould of plastic is the injection molding cycle
• The cycle begins when the mold closes and molten is injected into the mold

CORE DESIGN:

• The core part has projections , begin with extrapolating the Class-A surface and then its is trimmed with Class-C surface make sure that you trimmed properly(the extrapolated should be gone)

• Now the obtained trim is again trimmed with Class-B surface (we should see the parting surface and the part body above it )

• check whether edges are clearing or not (click on tooling axis select normal view and then zoom in to the draft areas if you can see surfaces then its clearing or else you need to modify the draft and tooling axis)

• Now the final core block is obtained by drawing the boundary sketch and extruding it along the tooling direction followed by filling and thickening

CAVITY DESIGN:

• core block is obtained by drawing the boundary sketch and extruding it along the tooling direction followed by Trimming with the Class-B surface and the filling

• Create solid parts of core and cavity

PARTING LINE AND PARTING SURFACE:

• Parting line is the intersection between parting surface and the component it splits core and cavity into two parts
• The parting surface acts as connectivity between core and cavity it lies outside the component
• The parting line is obtained by intersecting Class C+Class-A with Class-B surface