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

 Aim: Create the ribs & bosses for the drill handle.

Input Class A surface:

Draft analysis report for both the switch bezel plastic component :

Draft :

Draft angle is nothing but providing some tapered portion to the part for easy removal of the component from the mold during manufacturing. This is especially done in the case of plastic component design having a complex shape. Mostly the 3-degree draft angle is provided but it can vary depending upon the component which is to be designed

In our case of Switch Bezel design, the draft angle is 3 degrees the draft analysis is done during the design of the component to check the feasibility of the product.

Before providing a draft angle we need to decide on the tooling axis also known as the molding axis considering the faces which can cause issues while manufacturing.

Tooling axis :

It is nothing but the direction in which the mold opens and closes the draft angle needed to be provided by considering this tooling axis.

We can create a tooling axis by using the bisecting method.

Bisecting Methode :

This method is used for the generation of the tooling axis for that purpose first we need to decide the direction of molding and then we create one dummy tooling axis for the reference to the purpose.

In this method, we select the surfaces which can create problems and take intersections in the x and y-direction. By using these curves we draw two lines and then draw a bisecting line from these two lines in the x-direction and y-direction.

If it is done in x-direction then it is called a tooling axis clearing x-direction and if in y then tooling axis clearing y-direction.

After completing this we need to draw a final line bisecting this two tooling axis in the X and Y directions to get our final output.

Class A surface draft analysis:

3 Degree.

The above image shows the draft analysis in which green color surfaces shows that they are having an angle of more than 3 degrees but the surface in red color shows it is less than 3 degree that is having an angle of 0.98 degrees. These are the results of the draft analysis which are very crucial for determining the feasibility of the product.

0.98 degree.

Solid component draft analysis:

3 Degree.

0.98 degree.

Rib Design

CREATING THE RIB

Ribs are thin wall protrusions that extend perpendicularly from a wall or plane. They are usually found in clusters offering support to a plane that would have otherwise been too thick, but can also be stand-alone support for a single wall. They are commonly used to provide additional support and strength to a part. Thickness and location are essential to rib design.

First, the base surface where the rib has to be created is extracted using the Extract command. A positioned sketch is created and the profile for the rib is drawn.

Next, the profile is extruded, to find the height,h=Wall thickness * 5

                                                                                       =2.5*5

                                                                                       = 12.5 mm

Therefore, the height is 12.5 mm

The extruded surface is thickened,

Thickness,w=0.4*t

                 =0.4 2.5

                 =1mm

Therefore, the thickness of the rib is 1 mm

The draft is applied to the sides of the ribs. As per the design rule, the ideal draft angle is 0.5 deg

Then fillet is applied to the faces of the rib. As per the design rule, the fillet can be 0.25 mm.

Now, we have to check for the Rib root thickness.

To check for the Rib root thickness, We have to take an Intersection with the XY plane and the Coin holder component. Once we get to the intersection we have to create a tri-tangent circle at the rib area and measure it. The value must be within 30% greater of the wall thickness.

SCREW BOSS DESIGN :

CREATING THE SCREW BOSS

Screw 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. Their primary use is to strengthen holes or slots in the surface present in the part model.

The construction process of creating the screw boss is explained below:

For thickness, the design rule is as follows,

Thickness,w=0.6*T

=0.6*2.5

=1.5 mm

Therefore, the thickness of the boss can be 1.5 mm per side.

In this case, we have considered the size of the screw boss as M06.

Once the sketch is completed, then it is padded using the Pad'command. The height to diameter ratio can be 3:1

Next, the draft is given to the boss. As per the design rule, the draft given for screw boss is 0.5 deg.

Then fillet is applied to the faces of the rib. As per the design rule, the fillet can be 0.25 mm.