Week 12- Final project

DEVELOPMENT OF DOOR TRIM PANEL

OBJECTIVE: to make half of the door trim panel in catia-V5 from the provided Class-A surface and folloing the master section.

APPROACH:

1. Make tooling axis.
2. Run draft analysis.
3. Make B surface.
4. Make C surface.
5. Trim all together and make it a closed body.
6. Create a solid body from the closed surface.

CLASS-A SURFACE

In automotive industry various teams works on various components, a car for example is not entirely designed by a single designer. There are many teams among which the task of making various components is distributed. And this is followed for every department of the industry. In this project we are given class-A surface which is designed in other software like Autodesk Alias, by a class-A designer. This is aesthetic surface and a lot of time, effort and good experience are demanded for making this continuous and a good flowing surface model. This is the major reason why, when we get this as input we are not allowed as a plastic designer to make any improvements in the class-A surface. Rather, it should be brought to the attention of the seniors which later is conveyed to the concerned team and take care of.

TOOLING AXIS

Tooling axis is the axis along which the core and cavity opens and closes. It is very important to define the tooling axis in the first step while designing a component as it is the main component which helps us to run draft analysis on class-A at initial stage to see if we can move ahead. Also for later stage, tooling axis is the direction along which class-C surface and the draft to the components is given.

In this model we have a tooling axis in the perpendicular direction to the entire door trim that is y-direction in the model. It is very evident that switch bezel will require a side core, so another tooling direction is made specifically for switch bezel. Apart from these two tooling axes we also have a side core tooling axis for dog house.

DRAFT ANALYSIS

Our first step before starting the model should always be to check is the surface has enough draft that it will not create any problems while ejecting from the mold. This seems like a big task as we have to foresee something that will come at very later stage. But this is done by a small process called draft analysis. This analysis tells us whether our component will be safely ejected in the tooling axis we have provided. Some components require side core where there are under undercuts, holes or projections on the side walls, so for this we need a different tooling axis and a different analysis is required to check those areas. Draft analysis shows color codes which are defined by the user for different values which also are defined by the user. These colors help us to analysis if the component is clearing the analysis and we are good to go ahead or not. In case the component fails the analysis for class-A then we have to submit the draft analysis report to the higher authority so that the surface of the component can be improved. Failing analysis simply means that the component does not have the required draft value it must have. In case our solid model which we develop, fails the analysis at some parts then we have to correct it ourselves.

We have to make sure that our entire model is green which means it is clearing the analysis. So we have to run analysis for class-A, solid model and other B-side features as every single component, regardless of its size should be ejected safely from the core.

DRAFT ANALYSIS REPORT ON CLASS-A SURFACE

CLASS B SURFACES

CLASS C SURFACES

PART BODIES

DRAFT ANALYSIS ON PART BODIES

ASSEMBLY PRODUCT

CLASS B FEATURES

DESIGNING B-SIDE FEATURES

DOG HOUSE: Primary function of the dog house is to avoid sink marks. But it also helps in other things like if the mating part is to be at a greater distance then we cannot make the height of the screw boss of that greater height, thus we make dog house and mount screw boss on it. Hence it helps in solving the problem of screw boss and also it helps to have perpendicular screw boss.

GENERAL DESIGN GUIDELINES FOR DOG HOUSE DESIGN:

1. Minimum height: Less than 6mm causes steel condition.
2. 3:1 ratio of steel width to height. But 2:1 is preferred.
3. Minimum width: 3:1 ratio of steel width to height. But 2:1 is preferred.
4. Draft: minimum 1.5deg.
5. Sink saver: height= 40% of nominal thickness. Width= 3.0mm-6.0mm.
6. Optimal radius:25mm

SCREW BOSS: They are used for the purpose of mating two parts. They have hole in them which accepts the threaded part of the fasteners such as screws.

GENERAL DESIGN GUIDELINES FOR SCREW BOSS DESIGN:

1. Draft: 5 deg on each walls.
2. Wall thickness: 40% of the nominal wall thickness i.e. 0.4*t where t is the wall thickness which is 2.5mm in this case.
3. Height/diameter: 3:1 steel but 2:1 is preferred.
4. Radius of the fillet: minimum 0.25mm.
5. Boss gussets (rib like structure giving strength to the screw boss) must meet ribs guidelines.
6. Avoid merging the screw-boss into wide wall.

RIBS/GUSSETS: They increase the stiffness and strength without increasing overall wall thickness of the model which is not desired. They also facilitate:

1. Locating and arresting components of an assembly
2. Providing alignment in mating parts
3. Acting as stopper or guides for mechanisms.

DESIGN RULES FOR RIBS:

1. Draft: 0.5 deg per side (minimum), but this value should not be high enough that it will cause failure for other consideration. For example, more draft will result in less thickness at the top surface.
2. Thickness of ribs: 40% of wall thickness or 0.4*t where t is the wall thickness.
3. Height: ≤ 5 times the wall thickness i.e. 5*t
4. Spacing (for more than 1 rib): 3:1- steel height/width ratio (maximum). h/w =3or2(preferred) where h is the height of the rib and w is the space between two ribs.
5. Minimum thickness at the tip: 0.75
6. Radius: 0.25mm max
7. Ribs on opposite side of the wall should be offset
8. Ribs should be connected to other structural features where possible.
9. Rib root thickness should not be more than 30% of the wall thickness.

CONCLUSION

LOWER DOR TRIM PANEL IS CREATED

THANKYOU!!