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

Ribs and Screw Boss creation

Aim :

To create the Rib for the drill handle concidering the design rules for rib creation and Screw boss creation and then perform the Draft analysis for the final component.

Objective :

• Create the Tooling axis by using the bisecting method.
• Design the class-B and class-C surface and join them.
• Create the solid feature by surfaces we create.
• Design the required Ribs and Screw Boss and analysis them.
• Perform the Draft analysis for the final component.

Theory :

Tooling Axis :

Class-A surface is first analyzed to create the tooling axis or tooling direction that molds pull apart in injection molding. Tooling direction is important for plastic product design as it decides direction for mold seperation.

Step followed for creation of tooling axis :

• Reference point is first created on extracted surface.
• New axis system is deployed to plot clearance lines.
• The X-direction and Y-direction along the class-A were used to create tooling axis.
• Graphic properties of tooling axis were change before publishing.

Draft Analysis :

The Draft angle is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees. A functional part for injection molding has to have Drafts facing both cavity and core sides to reduce the risk of damge to the parts and ensure ejection. And also important is to overcome the vaccume forces by letting air in between the metal to the plastic for the part to release properly. Adding maintaining a decent cosmetic finish.

Draft should be a part of design for manufacturing and plastic product Designer should be aware of its need at the outset of the design process. This allows considerations for design requirement to be taken into account.

Nominal values for Draft angle :

• 3 Degrees is the nominal Draft angle.
• 7 Degrees for textured surface.
• At the minimum of 0.5 Degrees can be manufactured by special tools. But it will increase the manufacturing cost.

Tooling axis creation :

First step is to observe the given class-A surface deeply and we can say the larger flat area which is perpendicular to the Tooling axis. So, by considering this things for this class-A surface tooling direction will be in X-direction. so we create the point on the flat surface as shown in figure.

And next is to create the reference line or axis from the Z-direction using sketch and bisect line as shown in figure.

Similarly from the Y-direction also the reference axis is created as shown in figure.

Next step is to extrude this two line as the surfaces as shown in figure.

And now by using the intersetion tool by intersect the two surface we created and as the result we got on line. this line is the tooling axis as shown in figure.

And change the properties of the line to visual clearly change the color and line type as shown in figure.

Draft Ananlysis :

1. The part created has to be changed to material mode in display frame.
2. Compass is enabled and align it along with the tooling direction.
3. Lock command is then applied to fix compass along with tooling axis.
4. Color codes are classified and Draft angle is applied.
5. Running point analysis is used to display permissible draft angle.

Draft analysis for Class-A surface :

Given class-A surface :

Created class-B surface :

Created class-C surface :

Closed surface :

Solid body : Created by close surface tool

Create Ribs and Screw Boss

Sketch for create Ribs :

Sketch for create Screw Boss :

Tree structure :

Component with Ribs and Screw boss :

Analysis for Ribs Dimension :

The analysis for the dimension is the one of the very important analysis to avoid the problems in the injection molding process for the component dimesions. the problems like sink marks, flow lines, weld lines, warping. Then they create the some standard for the creating the ribs. That standard dimesion is as shown in figure.

Now we need to check our part by intersect line in the sketch environment as shown in figure.

Analysis and claculation : For Ribs

This analysis and calculation is done in excelsheet for better understanding the status.

Analysis for Screw boss Dimension :

The analysis for the dimension is the one of the very important analysis to avoid the problems in the injection molding process for the component dimesions. the problems like sink marks, flow lines, weld lines, warping. Then they create the some standard for the creating the ribs. That standard dimesion for create Screw boss is as shown in figure.

Now we need to check our part by intersect line in the sketch environment as shown in figure.

Analysis and claculation : For Screw boss

This analysis and calculation is done in excelsheet for better understanding the status.

Draft Ananlysis :

1. The part created has to be changed to material mode in display frame.
2. Compass is enabled and align it along with the tooling direction.
3. Lock command is then applied to fix compass along with tooling axis.
4. Color codes are classified and Draft angle is applied.
5. Running point analysis is used to display permissible draft angle.

Draft analysis for Class-A surface :

Iso-metric view :

Front view :

Side view :

Top view :

Conclusion :

Hence the Rib for the drill handle concidering the design rules for rib creation and Screw boss creation and Draft analysis is also performed for the final component is successfully done.