Week 8 - Challenge 5 - Core & Cavity Design

DRAFT ANALYSIS, PLASTIC COMPONENT MODELING AND CORE & CAVITY CREATION FOR SWITCH BEZEL

AIM:

1. To create the tooling axis for class A surface and To perform the Draft analysis for both the given Class-A surface and the final plastic component created.
2. To create the core and cavity design of switch bezel component.

OBJECTIVES:

SWITCH BEZEL

1. Explaining the Draft analysis and the Tooling axis creation.

2. Creating the tooling axis particularly the Bisecting method.

3. Draft analysis report for both the given Class-A surface and the final plastic component.

CORE & CAVITY DESIGN

1. Explaining the core & cavity, parting line & parting surface.
2. Creating the Core & cavity blocks, parting surface and parting line.

ABSTRACT:

DRAFT ANALYSIS:

The major consideration of Draft Analysis is whether sufficient Draft Angle is provided on the component. Components while designing should be provided with a considerable amount of draft angle depending on the manufacturing consideration. For Plastic components we provide a draft angle of 3 degree. But for Automotive Sheet Metal Parts, it will be from 7 degree or more.

TOOLING AXIS CREATION:

The direction in which the mold or core and cavity opens is the tooling axis. With the help of the tooling axis created along the x-axis and the y-axis, these tooling axes are used for creating by bisecting method. Where the two lines and point will be selected as inputs.

PROCEDURE TO PERFORM A DRAFT ANALYSIS AND TOOLING AXIS CREATION IN CATIA

STEP 1

Connectivity of Class-A surface:

First checking the connectivity of the CLASS-A surface, this can be done by creating boundaries or by using the join command and see how well it is connected. Just ensure there is no surface gap between component or surfaces. This is the first design step to check continuity and the Quality of the CLASS-A surface.

STEP 2

Analysis visually for the best possible tooling axis for the component.

Checking possibilities in all three x, y and z axis directions and finding what are the problem creation parts of the component.

The clearance checking along all the axis direction will be done by creating an intersection along an axis on a plane by creating a new axis system with the model and constructing two lines contact with the walls, the line bisecting the two lines and passing through the point will be tooling axis.

A Dummy tooling axis will be directly created using point-direction command after creating boundary for CLASS-A surface and creating intersection with the model

TOOLING AXIS CREATION:

Using the intersection created lines will be created along the inclined walls, these lines are used for creation of tooling axis by bisecting method where are two lines and point will be selected as inputs.

Creating intersection for checking along X-axis

Using the tooling axis created along x-axis, these are used for creation of tooling axis by bisecting method where the two lines and point will be selected as inputs.

Publication:

Publication is used to make easily accessible of the published components.

Draft Analysis:

Draft analysis is done after determining the tooling axis, draft analysis is used to check whether the minimum draft 3 degree is maintained or not.

Compass is used to define the draft direction

If the minimum draft 3 degree is provided the whole component changes into green colour.

CLASS-B surface:

CLASS-B surface is created by extracting each walls, base & bezel and un-trimmimng and extra-ploating the walls to obtain the shape by trimming the excess surfaces and offsetting it to certain distance based on the thickness of the model. The offset surface will be the B-surface.

CLASS-C surface:

The surface created using sweep command by sweeping the boundaries of A-surface along the tooling axis to connect from A to B-surface is known as C-surface.

Using the B and C surfaces created a closed surface will be formed by trimming the excess surfaces the surfaces will be converted into a solid model using Closed surface option.

DRAFT ANALYSIS FOR PLASTIC COMPONENTS;

Screenshots of the solid model with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

CORE AND CAVITY BLOCK DESIGN OF SWITCH BEZEL:

• The mold core and cavity are the shaped section in either half of the mold tool which give the plastic product its final shape.

• The hot molten material is injected in to the core and cavity and then sets hard in to shape. The design of the core and 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 in to the mold cavity.

• A core is usually made of the best quality sand and is placed in to 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.

CORE:

• The core design is started with extracting the parting surface that 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.

• At first the A-class surface is extrapolated with some length and later it is trimmed with a C surface.

• This A and C surface again trimmed with the B surface to form the core face.

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

CAVITY:

• 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.

• This outer surface is trimmed with the B class surface and then it is filled and thickened.

PARTING LINE AND PARTING SURFACE:

• A parting line in the 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.

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

SWITCH BEZEL MODEL

CORE AND CAVITY MODEL

FRONT AND BACK VIEW

TOP AND BOTTOM VIEW

RIGHT & LEFT SIDE VIEW

ISOMETRIC VIEW