Week 10 - Challenge 1- Attachment Feature Creation (Ribs & Screw Boss)

INTRODUCTION

Ribs and screw bosses are engineering features which are created on the B side of the plastic components

RIBS

Ribs are used to strengthen the walls of your mould without increasing wall thickness which means that you minimise the problems that come into play when the wall thicknesses have to be increased.

In essence, if the wall is too thick, warping and sinking can result so that the entire design may need to be rejected.

SCREW BOSS

Boss features are commonly found in injection molding designs. They are used to aid in the assembly of molded parts by providing a channel for a screw. Designing plastic screw bosses is fairly straightforward but there are a few considerations to ensure a strong connection between parts and mitigate cosmetic defects

OBJECTIVE

Create Tooling axis for the given CLASS -A surface.

Create the CLASS B and C surfaces of drill handle using the given CLASS-A surface.

Create final surface model and convert it into solid body using close surface command in the part design workbench.

Create ribs and screw bosses on the B surface by considering the design rules.

Perform draft analysis for both Class-A surface and Final part body

Design :

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

Tooling axis creation:

Manually arrange the view to choose the ideal tooling direction that covers the majority of the surfaces.

The majority of surfaces may be cleared by tooling in the Y direction. Hence, we may establish tooling axes in the y direction.

I have created tooling axis using normal to the surface method. For that extract a plane surface and create a midpoint on it.

Create a line on the point and direction along y axis.

Class b surface:

Class-B surface refers to a part's thickness that is both inside the component and not visible. To put it another way, a Class-B surface is one that is thinner than a Class-A surface. This is the area of a model where the engineering components are located.

Set the class apart-

a 2.5mm-wide surface that is angled inward.

Use extracted curves and multi section surface characteristics to work on the patches made on the offset surface.

The work surface can be joined, and continuity can be checked.

Class c surface:

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

Multi extract the boundary edges and sweep it with reference to surface at 90 degrees, this method is useful when the created sweep surface is facing perpendicular to the tooling axis.

C surface sweep which is creating parallel to the tooling axis should have at least 3 degree of angle value while sweeping to pass the draft analysis.

Create curves using extract feature and connect curve features to create sweep surface on the complicated regions

Create a final drill handle surface

And extrapolating the surfaces

Rib Creation

Draft: 0.5 Degree per side (minimum)

Thickness of ribs: 40% of wall thickness

Height: ≤ 5 times the wall thickness

Spacing (for more than 1 rib): 3:1- steel height/width ratio (maximum). h/w =3 or2(preferred) where h is the height of the rib and w is the space between two ribs.

Minimum thickness at the tip: 0.75

Radius: 0.25mm max

Guidelines:

ribs:

Tree structure:

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.

Procedure for performing the draft analysis are as follows

Change the view mode of the component to be in customized parameter mode and then select the shading mode as materials.

Then open the featured draft analysis tool from the insert menu.

Then click on use the compass to define the current drafting direction and then drag and align the compass on the Tooling axis.

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

view:

References:

Skill lync