Week 8 - Challenge 5 - Core & Cavity Design

AIM:

Create the core and cavity blocks for the switch bezel considering the all design rules.

OBJECTIVE:

• Create the Core and Cavity for the Switch Bezel.

THEORY:

TOOLING AXIS:

Tooling axis is the parameter which decides whether the tool enters into moulds or not as it denotes the draft clearance angle where a moulded part is removed from the mould.

DRAFTING ANALYSIS:

The Draft Analysis command enables to detect if the part you drafted will be easily removed. This type of 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.

PARTING SURFACE:

Injection mold has two major components the movable halve and the fixed halve, during the process these two halves to avoid the melt flow leakage and maintain certain holding pressure, the pressed surface are called Parting Surface.

PARTING LINE:

A parting line is the line of separation on the plastic part where the two halves of the plastic injection mold meet.

CORE:

The core is the male part which forms the internal shape of molding. The cavity is the female part which forms external shape of molding.

CAVITY:

The enclosed space between two mold halves which forms the shape of the desired part.

PROCEDURE:

Creating the Tooling Axis.

• First import the Class a Surface of switch bezel model in CATIA V5.
• Check the connectivity of class A Surface Using Boundary Options.
• Visually check which direction is better for creating tooling axis.
• First Create a dummy Tooling Axis in Z direction.
• Now Using the intersect option, select the YZ plane as first element and base bracket as second Element.
• Now create lines through the walls of a base bracket using point option with the help of intersect 1 where you think the tooling might create problem.
• Now using these 2 lines create a bisecting line from reference point in Z direction. This will form a main Tooling Axis in Z direction.

performing the draft analysis.

• Open Draft Analysis option form Insert>Analysis>Feature draft analysis.
• A new window pops by default it will be in quick analysis mode. Change the range to 2.9 deg.
• Next Position the compass on the tooling axis by dragging the compass from the top right corner of the working area. W axis of the axis system lie on the Tooling Axis.
• Then define the compass by click on the compass icon on the draft analysis window. Then lock the position of the compass by clicking the lock icon.
• After that select the surface and the whole surface will show a color range. If it Shows the surface in fully green. which means all faces are having a minium draft angle and its good for manufacturing.If any face is showing blue or red color we have to work on that face to give a good draft.

Creating Core and Cavity:

Parting surface design principles:

• Design the injection mold simple as possible. Avoid or reduce side parting as much as possible to reduce complexity of the mold making.
• Ease of de-molding as far as possible. for instance the plastic parts should stay in fixed halve of injection mold and should ejected by ejection system avoid.
• Ensure appearance requirement of molded parts. finish or mismatch usually occurs on parting surface, so the parting surface should not be designed on high quality requirement surfaces.

DESIGN OF CORE and CAVITY:

To extrapolate class A surface.

Trim class A with class C to get inside portion.

Now Trim the Class B surface with the above result to get the area of the core.

Extrude the sketch overall through the tooling direction to get the exact core portion.

Then we get the final output of the core design and closed part body of the core Design.

Final Core Part

Similarlly, Repeating the same as done for the Cavity part also and trim it on other side surface.

Final Close body surafces of core and cavity are..

Component with parting line and parting surafce

Cut section View and intersection here blue lines represents the Parting lines

Final output

CONCLUSION: The design of core and cavity is thus done.