Week 8 - Challenge 1 - Base Bracket Design

DESIGN OF THE BASE BRACKET

AIM:

To create the Base Bracket Plastic component through the given Class-A surface.

SOFTWARE USED:

Catia V5

DESIGN PROCEDURE:

IMPORTANCE OF TOOLING AXIS:

The Tooling Direction is the direction that the mould pulls apart. The mould is built into two separate pieces. You have a Cavity side and you have the Core side. The Core pulls apart from the Cavity and that's the Dyeline or the Tooling Direction. There are different methods to find out the tooling direction. Here we are using bisecting method to find out the tooling direction. We can use any method the ultimate aim is to reduce the cost of manufacturing by reducing the complicity in manufacturing the component.

• It is the direction in which the component will be ejecting after the molding process is completed.
• The direction of tooling axis should clear the maximum portion of the part.
• It should be selected in such way that number of side cores will be minimum as it will add more cost to the process.

IMPORTANCE OF DRAFT ANGLE:

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. As the molten plastic flows into the closed die and fills the cavity, the material shrinks inside the mold upon cooling and as a result grips the core. Draft angles should be at least 3° to facilitate the part ejection.

• Reduces the chance of damage to the part due to friction during release.
• Reduces wear and tear and chances of damage to the mold.
• Ensures a uniform, smooth, unscratched finish when required.
• Ensures the integrity and uniformity of other surface finishes and textures.
• Reduces overall cooling time by lessening or eliminating the need for unconventional ejection setups.

WORKBENCH AND TOOLS USED:

CATIA V5 - Generative shape design

• Extract
• Extrapolate
• Join
• Trim
• Offset
• Boundary
• Edge fillet
• Intersection
• Sweep
• Close surface
• Feature Draft Analysis

DESIGN TREE:

METHOD:

Step 1: Importing the Base Bracket File and Check Class A Surface design file:

After receiving the class A of the Base Bracket check for the connectivity of all surfaces on it. Use Join operation, boundary operation and disassemble. The check is over if any discontinuities do not arise. Delete the operations after the check.

After importing the class ‘A’ surface, we need to check the connectivity between the surface with merging distance 0.003 mm.

Step 2: Determine Tooling Axis:

Create a Dummy Tooling Axis along the best possible direction as per the Class A as shown below. In this case, we have chosen Z-axis as a dummy as it doesn't interfere with any slots or holes.

Create a new plane along YZ Plane and Intersect the plane and the Class A surface

Create extended Lines for the faces which may create problems in terms of Draft angles. In this case, the lines are created for each intersection.

Create a Bisecting Line for the extended lines long the centre point and name it as Tooling Axis

Now that the Tooling Axis is created let's Publish the Tooling Axis and the Class A Surface for quick access.

Step 3: Draft Analysis:

Change View Mode Customization to Material mode

Go to INSERT > ANALYSIS > FEATURE DRAFT ANALYSIS and move the compass to the Tooling Axis. Change the range to 3°. Apply the settings.

Uses the compass to define the new current draft direction.

Step4: Class B Surface:

Consider the thickness of the component as 2.5mm. Now we need to create a B surface which will be similar to the A surface at an offset value of 2.5mm.

First, we are creating the ribs in this operation. To create the ribs, first, extract the surfaces of it from Class-A Surface.

Once the surfaces are extracted, un trim them and then extrapolate them by 10mm by using point propagation. Now trim these surfaces and offset them to 2.5mm.

A similar process will be done on the other side of the Rib 2.

Now let's create the base of the brackets with the same steps which we used for creating the ribs and trim the base and the ribs to make a final trim off the part.

Towards the last part of creating the Class B Surface, we will join the Final trim part with the other base part to obtain the below Surface B.

Once all the surfaces are created trim these surfaces to form a Class B surface and give the appropriate fillets to form a Class B surface.

Step5: Class C Surface:

To create a Class C surface, first, extract the boundaries of the Class A Surface.

Now using the Sweep option create the surface. To perform this operation, Go to the Toolbar > Sweep > Profile type > Line > Subtype: With draft direction > Guide curve 1- (select the extracted boundaries) the in Draft direction (select the tooling axis) angle and length as 3° and 20mm respectively and click ok

The same process will be done for the holes, extracting the boundaries and using the sweep operation to form a surface.

Step 6: Joining the all surfaces:

Now we will use the Join command to join all the 3 Sweep operations that we have created. This will give us the Class C Surface.

After the creation of Class, A, Class B and Class C surfaces, we need to join Class A and Class C surface to form a new surface. Then trim the joined surface with Class B surface to form the final required surface.

Step 7: Closed body of BASE BRACKET:

Now that we have the required surface, we can make a solid body out of it. To make a solid body we will go to the Part Design section over there we will use the Close Surface tool to make a Solid Body.

Step 8: Validation of the BASE BRACKET:

Change View Mode Customization to Material mode

Go to INSERT > ANALYSIS > FEATURE DRAFT ANALYSIS and move the compass to the Tooling Axis. Change the range to 3°. Apply the settings.

Uses the compass to define the new current draft direction.

RESULT:

The Base Bracket has passed the Draft analysis test as the draft values of the Base Bracket are higher than 3° and the Bracket is safe for production.

Hence, Created the Base Bracket Plastic component through the given Class-A surface. Created the tooling axis for the given Class-A Surface which meets the requirements of the draft angle and the Draft analysis is analysed on the model.