Base Bracket Design

1.AIM

To Create a Solid part from the given Class A Surface as an input.

2. Other Objectives

• Creating tooling Axis
• Creating Class B Surface
• Creating Class C Surface

3. Class A Surface

Class A Surface is a surface with aesthetic shape with no thickness. After the completion of concept sketch it will be imported to any class A creation software like Alias and it will be given as an Input to a plastic designer to give it thickness and other Engineering features.
Before starting to design, the plastic designer should verify that all the surfaces were intact. .
If the input Class A Surface's were seperate surfaces then it should be joined using "Join Tool" from 0.001mm to a maximum of 0.003mm.

4. Creation of Tooling Axis

Tooling Axis is simply the direction where the mold opens and Closes. The part draft should be given along the tooling axis. Selecting the tooling axis will be crucial because it should be created properly to clear all the sides of the draft analysis.
Usually there are three methods of choosing the tooling axis direction and they are X, Y, Z direction, Normal to Surface and Bisecting Method.

5. Draft

In Plastic Molding, the property of every molten material is that once its solidifies it will tries to clinge on the core. Usually when an plastic component is molded without any draft angle then, it should have to undergo much friction with the Core and Cavity section.
This will leads to so much of wear and tear and it could leads to the damage of Core and Cavity.
Also the part which is created will also have some unpleasant surface finish and it also can be deform. So to avoid this, draft angle will be given.

This is why , while designing any plastic component there will be a minimum degree of 0.5 draft angle. But manufacturing such precise component will leads to the increase in budget.
So for normal surfaces, it will be mostly 3 degree of draft angle and for textured surfaces it will be 7 degree of draft angle.

6. Procedure

6.1 Class A Surface Check

The given Class A surface should be intact and should not have any open boundary inside the surface.

6.2 Tooling Axis Creation

The tooling axis was created by using bisecting method in the z direction. From the z view most of the Class A surface was covered.
From this direction there are 2 surfaces which has some angle towards the tooling axis and it has some difficulty of clearing the drafting analysis and the other surfaces are parallel and perpendicular to the tooling axis which has no issue of clearing the draft analysis from the z direction.
So, two lines were created tangent to these surfaces and the Tooling axis was created bisecting this two lines.

6.3 Draft Analysis of Class A surface

With the Tooling Axis created, draft analysis will be performed on the Class A surface with the nominal draft angle of 3 degree. In the Analysis, Green colour refers that the 3 degree of draft angle can be performed in this direction and red refers the opposite.

6.4 Class B Surface Creation

After clearing the draft analysis the each surface's of the Class A will be extracted except the filleted surface and then it will be offseted to 2.5mm which is the thickness of the final component.
Then each extracted surface will be untrimmed and extrapolated with point continuity for 15mm.

Then the extrapolated surfaces will be trimmed with reference to the Class A.

For the fillet radius, the fillets which are in outward direction, thickness will be added with the actual fillet radius and for the fillets which are in inward direction , thickness will be subtracted with the actual fillet radius which is taken from the Class A Surface as reference.

6.5 Class C Surface Creation

Class C surface can be created with two methods.

• If the Class C Surface was perpendicular to the Tooling axis then it will be created by using Reference to Surface method at 90 degree of angle along tooling axis direction.
• If the Class C Surface was Parallel to the Tooling axis then it will be created by using Draft Direction at 3 degree of angle along tooling axis direction.

In this Challenge the Draft Direction method was used.
Using boundary tool, the boundary was taken from the Class A surface. Using Sweep tool , the boundary as guide curve and tooling axis as draft direction with 3 degree of draft angle , Class C Surface was created. Using the same method two holes in the Class A was extruded using Sweep tool.

6.6 Final Part body
After the creation of Class A, B and C Surface, Class A and Class C surface will be joined along the two hole which was extruded and was renamed as Class A+C Surface.

Then finally, the Class A+C Surface will trimmed along Class B Surface to get final Close surface of the Part.

Then moving to Part Workbench, Using Close Surface Tool , the Close surface was converted into Partbody.
And there was a final draft analysis on the partbody along the tooling axis to make sure the Class A and C Surface clears the 3 degree of draft angle.

7. Conclusion

Tooling Axis was created. Class B and C Surface was Created. Part body was created with the input of Class A.
Final part body clears the draft analysis along Class A and C surface direction at 2.9 degree of draft angle.