Week 8 - Challenge 3 - Switch Bezel Design

Switch Bezel Design

Create the Switch Bezel Plastic component through the given Class-A surface and perform the Draft analysis on the model.

Understanding Draft for Plastic products

When developing parts for plastic molding, applying draft (or a taper) to the faces of the part is critical to improving the mold ability 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 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.

Create the Switch Bezel plastic component and perform draft analysis using Catia V5

1. Creating the tooling axis

Create Class A using scanned skin file for Switch Bezel-

Create a dummy tooling axis-

• On the basis of the visual study create a dummy tooling axis.
• For this it is necessary to consider holes and undercuts of the component.

Create a tooling Clearance in xz and yz plane-

• Intersect the class A surface with XZ and YZ plane.
• Using the intersect curves draw lines on the edges or line with some angle more than 3degree draft.

• Using these two lines create a bisecting lines (Tooling clearance in XZ and YZ plane)

Final tooling axis-

• Create a bisecting line (Final Tooling axis )Using the tooling clearances in XZ and YZ.
• Publish tooling axis and class A surface for convenience.

Although in this particular model Normal line on the base surface itself clears all the faces. But in the general it is advisable to follow standard procedure.

2. Draft analysis

• Set the compass in the tooling axis.

• Analyse at 3 Deg minimum draft.

3. Creating Class B surface

Extract surfaces from the class A surface for resting surface, base and sidewall surfaces.

• Untrim and extrapolate these surfaces to get suraces for Class B.

Offset these surfaces with 2.5 mm and trim off them.

Give fillets according to class A to get final class B surface

• Add the thickness 2.5 mm to fillet radius of A surface to get the outside fillets radius of B surface.
• Subtract thickness 2.5 mm from fillet radius of A surface to get the inside fillets radius of B surface.

This is important to get the uniform thickness, which further ensures that part will not have any plastic defects.

4. Creating Class C Surface

Create sweep surfaces from the boundary of class A with required draft of 3 degree.

• During design it is important to consider the draft direction because it decides the parting line of mold.
• Outward draft is necessary because then only the parting line will be on B surface which is required.

Publish Class C and B surfaces for convenience.

5. Creating solid model

Use all A, B and C surface and trim off with each other to get final surface model

• With the fill surface create solid model out of the surface model.

Draft Analysis-

• In these models where C surface is in parallel to tooling direction, A and C surface should be in same colour during draft analysis regardless of the pulling direction

As the model lies in green zone in the draft analysis which suggests that all faces have minimum 3 degree draft angle, which further makes the part manufacturable.