Door Arm Rest Week 8 Challenge

Door Arm Rest Design

Create the Door Arm Rest 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 Door Arm Rest plastic component and perform draft analysis using Catia V5

1. Creating the tooling axis

Create Class A using scanned skin file for Door arm rest-

Create a dummy tooling axis-

• On the basis of the visual study create a dummy tooling axis, extract base surface create point and create a normal line (Dummy tooling axis) through that point.
• 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 and create bisecting line (clearance in xz plane).

• Using the intersect curves draw lines on the edge and create a inclined line (clearance in xz plane) with appropriate angle.

Final tooling axis-

• Create a bisecting line (Final Tooling axis )Using the tooling clearances in XZ and YZ

2. Draft analysis

• Set the compass in the tooling axis.
• Analyse at 3 Deg minimum draft.

Slider Tooling Axis-

As this is evident that with main tooling axis the pocket region of model will not be cleared so it is necessary to provide a side core/slider for this model which will be for the front pocket region.

• Extract front wall surface, create a center point and create a normal line (slider tooling axis) through that point.

Publish both tooling axis and class A surface for convenience

Draft analysis-

3. Creating Class B surface

Extract surfaces from the class A surface of two halves of the suface model.

• Trim off these surfaces and offset with 2.5 mm.
• Provide fillet according to the class A surface.
• Trim off Both the surface with a connecting surface.

First Half-

Secong half-

Final Trim-

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

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

• Offset these surfaces with 2.5 mm and trim off them.

Final tirim -

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 B and C surfaces for convinience.

4. 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

Main tooling axis

Slider tooling axis-

• In the model, 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.

Thus all of the regions are cleared using main tooling axis and side core tooling axis for Doorm Arm Rest Plastic Component.