Week 8 - Challenge 2 - Base Bracket Design

Base Bracket Design

Aim: - The aim of this report is to create the base bracket plastic component through the class-A surface in catiaV5. (Computer-aided three-dimensional interactive application).

Objective: -

1. To create the base bracket plastic component through the class-A surface in catia.
2. To create the tooling axis for the base bracket model meeting the requirements of the draft angle.
3. To perform a draft analysis on the base bracket model to confirm the appropriate draft angle.
4. To publish the class A surface and tooling axis using the publication command in the software.
5. To explain the bisecting method used in order to create the tooling axis for the base bracket model.

Theory: -

1. Tooling axis creation for base bracket model: -

The tooling axis indicates the direction along which the tooling or the manufacturing of the component will be done. In catia, the tooling axis is used to create a solid model from the surface body using the sweep option (basically called class C surface). There are many methods for the creation of the tooling axis and bisecting method is one of them.

figure 01: - Example of tooling axis direction

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figure 02: - Use of tooling axis in catia

The steps involved in creating tooling axis using the bisecting method are as follow: -

1. Check continuity or quality of class A surface
2. Selection of best possible tooling direction
3. Creating dummy tooling axis
4. Tooling clearance for respective directions
5. Creating final tooling axis

step1: -

Product designers should check the continuity or quality of the class A surface given by the class A engineer. They should ensure that there are no gaps between the surfaces using the boundary or the join command in catia.

figure 03: - Checking the continuity

step2: -

The tooling direction should be in such a way that it should cover the complete component along with its holes, undercuts, etc. in the main tooling. The product designer should also avoid side cores because the side cores generally increase the manufacturing cost of the component.

figure 04: - Base Bracket Model (class A)

figure 05: - xz direction

One cannot select the xz direction shown in figure 05 because it does not cover the holes which are at the top of the component in the main tooling. To cover that holes, one needs to make side cores for it which will cost a high for the manufacturing of the component. Hence, xz direction is not suitable to be the tooling direction.

figure 06: - yz direction

One cannot select the yz direction as shown in figure 06 because it does not cover the hole which is at the top of the component in the main tooling. To cover that holes, one needs to make side cores for it which will cost a high for the manufacturing of the component. Hence, yz direction is also not suitable to be the tooling direction.

figure 07: - xy direction

One can select the xy direction as shown in figure 07 because all parts along with the holes are getting clear in the main tooling without any side cores. Hence, xy direction is the best possible direction in this case.

step3: -

The dummy tooling axis is a line or an axis created at the center of the hole along xy direction as shown in figure 08. The dummy tooling axis is used just as a reference and it is not the real tooling axis.

figure 08: - Dummy tooling axis

step4: -

After selecting the main tooling direction, it is important for a product designer to see that all the surfaces along xy, xz and yz should be clear in the main tooling. Now, the surfaces perpendicular to the tooling direction is quite easy for manufacturing in the main tooling but the surfaces with a draft angle that are parallel to the tooling direction are a little difficult to manufacture in the main tooling. Hence, tooling clearance for such surfaces with draft angles that are parallel to the tooling direction is created to further create the main tooling axis.

In figure 05, all surfaces are perpendicular to the tooling direction. Hence, it is quite easy to manufacture it in the main tooling. In figure 07, all surfaces are perpendicular to the tooling direction. Hence, it is quite easy to manufacture it in the main tooling.

As shown in figure 06, two surfaces with a draft are parallel to the tooling direction. Hence, it is a little difficult to manufacture it in the main tooling. Therefore, tooling clearance for these surfaces will be created by bisecting these two surfaces.

figure 09: - Tooling clearance along yz direction

Line 1 and Line 2 representing the surfaces with draft angles parallel to the tooling direction as shown in figure 09 will be bisected to form line 3(bisected line) which is the tooling clearance along yz direction.

step5: -

Since there are no other bisected lines means there are no other surfaces that are parallel to the tooling direction which is difficult to manufacture. Hence, the bisected line created along the yz direction shown in figure 09 will be the main tooling axis.

2. Publication: -

Using the publication option, the important parts of a model are easy to search.

figure 10: - Class A, B, C, and tooling axis are easy to search

3. Draft Analysis on Fan Cover Model: -

Draft: - Draft is providing angles or tapers on product features such as walls, ribs, posts, and bosses that lie parallel to the direction of release from the mold that eases the part ejection.

The draft is required on all parts in the direction of mold movement in order to allow parts to release or eject from the mold properly. The draft is the angle at which the part is tapered to allow it to release. As the part cools, it tends to shrink to the core side of the mold. Adding draft helps the part to release. 3 degrees is the nominal draft. Whereas, 0.5 degrees can also be manufactured at ribs. 7 degrees for the textured faces.

figure 11: - Example of draft

Draft analysis is used to confirm the appropriate draft angle required for the component that is to be manufactured. Quick analysis mode, show or hide color scale, and analysis under the running point are the three main features used in the draft analysis. The color scale shows the draft angle for different colored areas and the analysis under the running point shows the draft angle at different points.

figure 12: - show or hide color scale feature

figure 13: - Analysis under the running point feature

Screenshots of the Draft analysis report for Class-A surface of base bracket model: -

1. Image of the complete Draft analysis: -

2. Images of the color scale variant: -

3. A model with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View): -

Screenshots of the Draft analysis report for a final plastic component: -

1. Image of the complete Draft analysis: -

2. Images of the color scale variant: -

3. A model with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View): -

Base Bracket final design: -

1. Class A, B and C surfaces: -

2. Final plastic component: -

Conclusion: -

1. Confirming the appropriate draft angle required for the component to be manufactured is one of the important aspects before continuing the design further.
2. Adding a draft helps the part to release from the mold.
3. The draft is important because it prevents the component from having damage while coming out of the mold.