Week 8 - Challenge 6 - Core & Cavity Design
AIM:
To create Core and Cavity blocks for a switch bezel from the given class - A surface.
PROCEDURE:
CLASS A- SURFACE :
TOOLING AXIS :
In order to obtain the proper draft analysis tooling axis is required and the following steps show how it is done.
As this component has 1 hole from where the tooling axis can be generated, however it does not have proper 4 walls to generate it. In this case, an approximation is made in order to obtain the tooling axis.
First by using the two side walls a dummy axis is made. As it is known that the draft angle is 3 degrees, the second axis is taken as a 3 degrees to the given wall and using these two axis the tooling axis is made.
Screenshots of the Draft analysis of Class-A surface:
DRAFT ANALYSIS ON CLASS-A SURFACE:
- Go to insert> analysis> feature draft analysis
- Align the tooling axis with the compass.
- Click on the surface and see that the surface is within the permissible limit of the draft values.
- The surface should be green and in the column nominal value 3deg given as input. hence the draft analysis on the class-A surface is successfully performed.
CLASS B- SURFACE :
CLASS C- SURFACE :
Class C Surface has swept along the boundary CLASS A surface with respect to the tooling axis direction with a draft angle of 3 degrees.
SWITCH BEZEL CLOSED SURFACE :
SOLID MODEL :
Core and cavity design:
The Mould 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 injected 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 mould of a plastic part is called the injection molding cycle.
The cycle begins when the mould closes, followed by the injection of the polymer into the mould cavity.
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.
Here intersecting the parting surface, core, and cavity across the ZX plane gives the intersecting line that tells the parting line.
Parting surface:
The parting surface of a mould are those surfaces of both mould plates adjacent to the impressions which butt together to form a seal and prevent the loss of plastic material from the impression. The parting surfaces of a mould are those portion of both
mould plates, adjacent to the impressions, which butt together to form a seal and prevent the loss of plastic material from the impression.
Tree structure :
Result:
Core and Cavity blocks for the Switch Bezel have been successfully created