Week 8 - Challenge 4 - Coin Holder Design
AIM
To Create the Coin Holder 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 at the end perform the Draft analysis on the model.
Firstly, the connectivity of the given Class-A surface must be checked, and ensure that there are no gaps between the surfaces.
It is clear from the above image that all the surfaces are continuous without any gaps in between them.
We can further disassemble the boundary so that the continuity is clearly visible.
Creation of tooling axis for the given Class-A surface
- Tooling Axis direction is the direction in which the core and cavity open.
- The selection of tooling direction depends upon the product and the features of the product.
The tooling direction is selected by visually checking the part and in such a way that there are no additional side cores required for the moulding process. This ensures proper clearance of the part after the process.
Extract the flat base surface and create a center point. Insert the axis system at that center point.
since the Class A surface walls are not having a proper draft angle we take the tooling axis normal to the base surface.
Class B surface
It is a surface that is below a certain thickness from the class A surface. The engineering features of the product are on the class B surface while the class A surface is the styling surface.
Extract the sidewalls of the component and Untrim them.
Extrapolate the untrimmed surfaces.
Trim the extrapolated surfaces.
The trimmed surface is offset by 2.5mm.
The base surfaces are extracted and untrim operation is performed.
The surfaces are then extrapolated and offset for 2.5mm
The top wall is extracted and is extrapolated.
The extrapolated top wall is then offset by 2.5mm.
The sidewalls, the base, and the top wall are trimmed together.
The top flange is extracted from the class A surface into two parts then it is extrapolated.
The two parts of the top flange are trimmed together.
Class C Surface
The Class C surface is the surface used to join class A and the Class B surface.
Class C surface is created using the sweep command with outer flange as reference surafce.
Fillets are added in the B surface.
the class c surface is trimmed with the class B surface.
The class A , Class B and the class C surfaces are joined together.
The slot is created using multiple extarct , sweep and Trim commands.
The projection in the class A surface is extracted, untrimmed and extrapolated.Then the extrapolated surface is trimmed as per the class A and is offset by 2.5mm.
The offset surface is then trimmed of from the main class B surface.
The above image shows the Final surface outcome.
The surface is then converted to a solid body by the Closed surface command.
front view
Left side view
Top view
Draft Analysis
When developing parts for plastic injection molding, applying a draft (or a taper) to the faces of the part is critical to improving the moldability of your part. Without it, parts run the risk of poor cosmetic finishes and may bend, break, or warp due to molding stresses caused by the plastic cooling. Equally important, an absence of a draft may prevent parts from ejecting from the mold, damaging not only the parts but possibly the mold itself—a costly and time-consuming detour.
In CATIA the draft analysis can be found by Insert > Analysis> Feature Draft Analysis.
Generally, the nominal draft angle will be 3 degrees.
Draft Analysis for the class A surface.
Front view
Left side view
Top view
DRAFT ANALYSIS OF THE SOLID PART
Left side view
Front view
From the above images it is clear that the draft angle provided in the class A surface is not proper. Hence changes must be made in the class A surface.
