Week 9 - Attachment Feature Creation (Ribs & Screw Boss) - Challenge 1

OBJECTIVE

• Create the rib for the Drill Handle considering the design rules mentioned in the video.

• Create the Screw boss for the Drill Handle considering the design rules mentioned in the video.

  General Guidelines for Bosses:

  • Draft - 0.5 degrees on the walls of boss
  • Thickness - Typically 40%* of the nominal wall at the base.
  • Height to Diameter Ratio - 3:1
  • Radii - 0.25mm maximum radii.

DESIGN METHODOLOGY

1. Input Surface:

Skin data would be provided to us by the styling team to us.

Class-A surface means visible surface. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.

2. Continuity Check:

The first step is to check the continuity of the class A surface. This is to ensure that there is no gap between surfaces. If we find any then we should fix that first.

• Analyse the class A surface through visual inspection.
• To make sure that the given surface has no gap in between them.
• We can check it also with the help of Join or boundary commands.

3. Creating the tooling axis

Tooling axis represents the opening and closing of the mold core and cavity during the manufacturing of the components. A plastic product designer should consider the best tooling direction to cutdown the cost of the component very less.

• Check the best tooling direction for the given surface.
• We can find out the best tooling direction by cross checking all the three axes.

• Here we can find out that the best tooling direction for the Door handle class-A surface is along x-axis direction
• The method I choose to create the tooling axis is first extracted a surface and create a midpoint on that surface.
• Then introduce an axis system on that point.
• Then created a with the point and direction along y axis.

Bisecting Method:

• Another method is by creating intersection along y direction. And then create lines on the walls and then create a bisecting line with the lines on the wall and point created earlier. We will get an axis which will satisfy the draft analysis requirement.

4. Draft analysis

The Draft Analysis is a command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on colour ranges identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.

Draft analysis is done after determining the tooling axis, draft analysis is used to check whether the minimum draft (3 degrees) is maintained or not.

• The part created has to be changed to material mode in display frame
• Then by enabling compass definition the axis system is pan along the direction of the part and aligned in line with the tooling direction
• Lock Direction is applied that fixes the compass and then the mode dialog box is formed by snapping at any point on the part
• The Color Codes are classified and Draft Angle are applied
• Then the Running point analysis is used to hover around the part to analyze the permissible draft angles and the analysis is saved

• Then lock the draft direction and perform draft analysis by clicking on the component.
• The green colour shows the positive daft tooling direction and the given surface passes the draft analysis.
• Click on the analyses under the running point to check the draft analysis on the individual faces. It shows how much draft on specific points when we move the cursor point.

5. SURFACE-B CREATION

Class-B surface means thickness of a part it is not visible and is inside part. In other words, Class-B surface is a surface below a certain thickness from the class-A surface. This is the surface that contains engineering aspects of a model.

• Offset the class-A surface to 2.5mm inward direction.
• Rework on the patches and discontinuity of the offset surfaces using the features like extract, multi-extract, sweep, multi-section surfaces, extrapolate.
• To ensure the continuity of the Class-B surfaces check the boundary command to find out the boundary.
• Hence class-B surface creation is done.

6. SURFACE-C Creation

Surface that joins class-A and class-B surfaces is class-C surface. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled

• Extrapolate and trim off the sweep surface corners at the required edges.
• Join the sweeps using the join command and the class-c surface is created.

7. Creating the final surface of Door Handle

• First step is to join the CLASS-A surface with CLASS-C surface.
• Then Trim the Joined surface with CLASS-B surface to achieve the final Bumper surface.

8. Creating Solid Body out of surface

Go to the part design work bench and using the close surface command create the Door Handle solid part body

Draft Analysis of 3D Part model in various orientations.