Challenge

Week 9 - Project - Master Section Development

GGokul Shyam22 Jul 2021

A class-A and Master sections from a vehicle component's surface are provided to me to design a part model and validate it.

From this B Pillar RH as a Class - 'A' surface, first I need to check whether the surface has some boundary irregularities and any open boundaries.

After checking I need to create a Tooling Axis for the Class - 'A' surface. And also if I need to create the Side core tooling axis for the surface.
Then I need to create the Class - 'B' and Class- 'C' surface with the help of the Class - 'A' surface And Master sections provided.

Two master sections (MS) have been provided to extract some data from it. By observing the master section, it is clearly in view that in master section 2 there are flanges fixed to the Class -Surface. So after creating the tooling axis I'll create the flanges for class A and then go for the other Surfaces.

Tooling axis creation

The tooling axis is the direction of drawing a sheet metal where the finished component is easily ejected on a particular direction and axis. The tooling axis is important for removing the material when finished. In this provided surface there are two ways to create a Tooling axis, which are-

First, I will create an Axis system, from that axis system I will get two cross-sections. by using that cross-section lines I will create the tooling axis for the surface.
Secondly, there are 2 MS provided, in that MS I can extract some of the geometry which will be the tooling axis because those MS should have been created by Parent tooling axis and a lot easier than the first option.

I will create a tooling axis by extracting some geometries using both MS.

After creating the tooling axis I'll create the side flanges as given in the master section. and then I will do drafting on the surface.

Now performing Draft analysis to check whether the tooling axis has some negative draft
A minimum of 3 degrees should be cleared to manufacture.

some facts are not cleared in the draft analysis let's examine them closely

As we can see, these red and blue surfaces are almost or equal to 0 degrees.

Now, this is an issue because it will not compete with the recommended classifications of a plastic part manufacturer.
If the surfaces are at 0 degrees the plastic part won't eject at the end due to contraction after the cooling process.

To tackle this problem there are mainly two reasons which I have come to know.

one way is to create a secondary and tertiary side core tooling axis to overcome this problem, but the overall point is to manufacture the product with fewer expenses.
So what I would recommend to the Class - A surface creator to give some draft angles on these sides for 3 to 7 degrees draft to negative sides.

- Now keeping the draft issues aside, I Will now Create the Class - B and Class - C surface.

Creation of Class - B surface

By checking the Master section, the thickness of the B pillar part is about 2mm. So offsetting the Class A surface without the flange to 2 mm and then making the flange for class B separately.

Class - C surface

By extracting the boundary of the class - A surface, the surface required for class - C is obtained.

Trimming and joining all the class surfaces together

Final output

Draft Analysis report

When a plastic component is made, we can observe a draft angle given on each side from the base that is lesser than 90 degrees. This is because in the criteria of making a plastic material the mold should release the material when finished. if the mold surfaces are 90 degrees the material won't release from the mold because of friction due to contraction of material when cooled.

To resolve this problem we CAD engineers maintain a standard rule to design the plastic mold or die's in such a way that there is no problem while ejecting the plastic component. So a minimum of 3 - 10 degrees of draft angle is given to every plastic component while designing.

The 'A' side

The 'B' side

the parting line should be formed on the B side edges, So Class A and C should be green.

Final model. After designing the Class - B and Class - C surface I will now continue to the designing of Locator, Dog house, and Ribs with the help of the Master section.

Draft Analysis report

The 'A' side

The 'B' side

the parting line should be formed on the B side edges, So Class A and C should be green.

Final model. After designing the Class - B and Class - C surface I will now continue to the designing of Locator, Dog house, and Ribs with the help of the Master section.

Dog house creation

the function of the dog house is to elevate the screw boss or any other part to touch the datum surfaces. in some cases, the fixing part is not touched by the plastic part to tighten, so a dog house is used to resolve this problem.

The intersection part where the main part and dog house meets should have the 40% of thickness to the main part.

and the height of that intersection should be 3 to 6 mm and it should be linear to the tooling axis.

The thickness value at the intersection is 40% of 2 mm

which is 0.88 mm, and after applying the draft value the thickness at one side is .88 mm and at another, it is 0.65 mm.

I have used the data from master section 1 and made the following dog house.

So what are Locators?

Locators work as a 3 - 2 - 1 principle which is basically to fix a component to be machined or to be placed in an ideal position. There are a total of 12 degrees of freedom, 6 rotational and 6 translational.

In this, I need to fix any 11 degrees of freedom permanently and anyone to be clamped or fixed temporarily. In this scenario, Locators come into place. there are 4-way locators, 3-way locators, and more.

4 - way Locators