Week 8 - Challenge 2 - Base Bracket Design

                                                                            BASE BRACKET DESIGN

OBJECTIVE: 

                  Create the Base Bracket Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the requirements of the draft angle and at the end perform the Draft analysis on the model. 

Tooling Axis:

• 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.

Why Draft Angle is Important:

However, they are a required feature. 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 Process in CATIA V5

Given Data,

Class A surface,

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

        Now we will be doing Draft analysis on Class ‘A’ Surface, for that we need tooling Axis

        As we can see that in X and Y direction the holes will not be clearing the tooling axis, so we will be taking Z direction as tooling axis.

   Creating the dummy tooling axis in Z direction, refer below image

DRAFT ANALYSIS USING BISECTING METHOD:

           First, we will be taking intersection curves of given surface and creating the lines through points on the faces of which we think can affect the ejection.

           By using intersection command on surface workbench create an intersection between ZY plane and the Base Bracket surface.

        Create lines by using points on faces which you think will create an issue. Make sure these points will clear the dummy tooling axis.     

         Now create a line by using Bisecting Line command which is in line feature and select those two lines which are passing through the faces. these bisecting command will create a mid-line between those two lines and name the bisecting line as toolin clearance line in X direction.

        This line is the Main tooling axis for our part.

        After which we will be publishing the tooling axis and class ‘A’ surface.

                                                                                DRAFT ANALYSIS

• Insert -> Analysis -> Feature Draft Analysis
• Keep the view mode to material.
• Drag the compass (Direction – compass) on the tooling axis and then select proper direction and lock it.
• Giving draft angle as 3 degree.
• The first step in the draft analysis part is to check the given class A surface is joined properly or not. this can be done by observing the part visually by using join command as shown in below figure.

     from the above image we can clearly observe that the surfaces are joined properly.

• Make sure that in customize view parameters command in shading it has to be material as shown in below image

• Go to insert>>Analysis>>Feature draft analysis.

• Make sure that in customize view parameters command in shading it has to be material as shown in below image

• Now drag the red coloured point on the compass to match the tooling axis which we have created.

• Click on the lock icon under the display command and a point will appear on your screen and tap the point on the surface of the Base Bracket.
• Change the angle from 2 degrees to 3 degrees on draft analysis.2 dialogue box and on draft analysis dialogue box click ok. the below image shows the enlarged draft analysis dialouge box.
• Now go back to lock icon and click ok. and see how the object apperance. if it is in green colour we can say that the object is fine and we can proceed with that if it is showing in any other colour such as blue or red we have to modify our design.

                                                                        PUBLICATIONS IN CATIA

A publication acts as a reference to a geometric or datum entity in CATIA V5. In 3DCS Variation Analyst CAA V5 Based, users can use published surfaces that copy the surface name, surface color and other properties. Here in our draft analysis we have published our tooling axis and Base Bracket.

‘B’ Surface Creation:

• Extract Class ‘A’ Surface.
• Untrim extracted surfaces.
• Extrapolate to some extend eg. 10mm.
• Use trim and select proper surface.
• Offset inward at 2.5 mm
• Use edge fillet, for inside fillet formula is Class ‘A’ surface Fillet + Thickness

‘C’ Surface Creation:

• Take outer boundary using Boundary command of class ‘A’ surface
• Use sweep command to create surface using tooling axis and draft angle as 3 degree.
• Take holes boundary and do step 2.

Final Body creation:

• Join class ‘A’ surface and ‘C’ surface.
• Trim resulting surface with ‘B’ surface.
• Join the surface.
• Result is complete close surface.

Solid Body:

• Change to Part workbench.
• Create Body.
• Surface Base Feature – Close surface – select last join.

TREE STRUCTURE:

                                                 VIEWS OF BASE BRACKET AFTER PERFORMING DRAFT ANALYSIS

FRONT VIEW:

SIDE VIEW:

TOP VIEW:

ISOMETRIC VIEW:

CONCLUSION:

           And hence, Here I am concluding that the draft analysis on a Base Bracket has been performed successfully and the report has been prepared by attaching all the images which are required.