Week 8 - Challenge 1 - Base Bracket Design

Base Bracket Design

Aim :

To create the base bracket plastic component through the given class A surface and create the required Tooling axis and perform the Draft analysis on the model.

Objective :

• First create the required correct Tooling axis and preform the Draft analysis on the given class A surface.
• Create the Class B surface and Class C surface by using the surface modeling tools.
• And make the closed surface of Class A, Class B and Class C as the single solid body.
• And perform the Draft analysis on the solid model.

Theory :

Tooling Axis :

Class-A surface is first analyzed to create the tooling axis or tooling direction that molds pull apart in injection molding. Tooling direction is important for plastic product design as it decides direction for mold separation.

Steps followed for creation of tooling axis :

• Reference point is first created on extracted surface.
• New axis system is deployed to plot clearance lines.
• The X-direction and Y-direction along the class A were used to create tooling axis.
• Two clearing lines were bisected to form tooling axis.
• Graphic properties of tooling axis were change before publishing.

Draft Analysis :

The Draft angle is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees. A functional part for injection molding has to have drafts facing both cavity and core sides to reduce the risk of damage to the parts and ensure ejection. And also important is to overcome the vaccume forces by letting air in between the matal and the plastic for the part to release properly. Adding maintaining a decent cosmetic finish.

Draft should be a part of design for manufacture and plastic product Designer should be aware of its need at the outset of the design process. This allows considerations for design requirements to be taken into account.

Nominal values for Draft angle :

• 3 Degrees is nominal values.
• 7 Degrees for textured surface.
• At the minimum of 0.5 to 1 Degrees can be manufactured by special tools. But it will increase the manufacturing cost.

Tooling axis creation :

First step is this observe the given class-A surface deeply and we can say the holes present side will be the tooling axis and also check with the larger flat area which is the perpendicular to the axis. so by considering this things in this class-A surface the tooling angle will near the Z-axis. so we creat the point inside the surface as shown in figure.

From that point and the Z-axis we create the line as shown in figure.

Then the next step is to take the some angle places and draw the line there. so we create the intersection line on the surface about the YZ plane as shown in figure.

In that intersection lines we need to create the lines which is goes through that intersection line both sides as shown in figure.

And next step is to create the line which is inbetween the two lines. For that the Bisecting line tool will use to create that inbetween line correctly. And this line is the Tooling axis and change the color and line type as your need.

Steps followed for Draft Analysis :

1. The part created has to be changed to material mode in display frame.
2. Compass is enabled and align it along with the tooling direction.
3. Lock command is then applied to fix compass along with tooling axis.
4. color codes are classified and Draft angle is applied.
5. Running point analysis is used to display permissible draft angle.

Draft analysis for CLASS A surface :

Class-A Surface :

The Class-A surface is the outermost surface of the plastic component which is also looks fine surface and it is the aesthetic surface that the designer creates as an input part for the design work.

Class-B Surface :

This is the surface that has a specific thickness from the class-A surface is the class-B surface. This is the surface that contains all the engineering aspects of a model.

Class-C Surface :

This is the surface that joins the class-A surface with the class-B surface is a class C surface.

Tools used for create surfaces :

1. Surfaces

2. Operations

3. Wireframe

4. Surface Based Features

Given Class-A surface :

Created Class-B surface :

Created Class-C surface :

Combined surfaces :

Solid Body : created by close surface tool.

Tree Structure for creating this Class-B surface and Class-C surface :

Draft Analysis for Solid body of Base Bracket :

Iso-metric view :

Front view :

side view :

Top view :

Conclusion :

Hence the base bracket plastic component through the given class A surface and created the required Tooling axis and performed the Draft analysis on the model and also for the solid model. so this Draft analysis feature is very useful to check the Draft angle and can chech whether this part is make any problem while manufacturing that product. And the nominal Drafting angle is 3 Degree so we need to design the part with minimum of 3 Degree has the Draft.