Week 8 - Challenge 1 - Draft Analysis on a Fan Cover

DRAFT ANALYSIS ON A FAN COVER

OBJECTIVE

Major objective is to perform the draft analysis on the part and ensure it has the sufficient amount of draft on its required faces, and also to determine the Main tooling axis for the draft analysis.

DRAFT

First we need to know what is draft. Draft is the predetermined taper angle given with reference to the tooling axis. Tooling axis means it is the direction of the mold opening and closing or the direction of the ejection of the component from the injection moulding machine. The below image shows the draft given in a component.

The above image shows the draft, every plastic part which have to be manufactured using injection moulding should have a draft. Giving a minimum draft angle of 3 degrees will helps to avoid the wear and tear in the core and cavity of moulds. This will help to increase the tool life, finally it will not only reduce the cost but also increases the surface finish quality of the plastic part produced by avoiding the scratching of the part along the faces of the mould.

Various draft angles are given according to the component, for plastic part 3 degree is given. For features in the injection moulding components like ribs etc., 0.5 degree is given, and 7 degree of draft is given for grinding surfaces like IP panel etc.

DRAFT ANALYSIS

Draft analysis is the tool used in CATIA to find out the draft given on the faces according to the main tooling axis, and as a result the CATIA will produce the colour codes which shows that the required draft is achieved or not. The detailed steps for achieving the draft analysis is given below.

Checking for gaps in the class A surface, all the areas of the class A surface should be joined without any gaps on it. We can check it using two ways by using the join command or by using the boundary command, for the join command we have to select the surface in the join command to see the boundary is created or not, this boundary is created when there is no gap in between the surfaces. In the another method of boundary creation there is no any open profiles in the final output and there should be only two domains after the disassemble of the boundary, reference pictures are shown here,

After checking the class-A surface we need to check the proper axis for the dummy tooling axis, this tooling axis can lie on any one of the xy, yz, zx planes. For the below shown model the dummy tooling axis is created on the z direction. It is shown in the below image

After creating dummy tooling axis we have to find the surfaces along the x or y directions which will make complications in the main tooling direction, in other words we have to solve the faces which are near parallel to the dummy tooling axis, and with the help of the line created on the problem creating surfaces we will create the tooling clearing x direction and tooling clearing y direction lines.

Tooling clearing x direction

similarly, with the use of the bisecting line command image for tooling clearing y direction is also shown.

Bisecting line is the command which is present inside the line command and for the creation of the bisecting line command we have to select the first line second line and a point, and a correct direction of the bisecting line, it is shown below

Now with the help of the tooling clearing lines on x and y directions the tooling axis is created, this tooling axis is also known as main tooling axis. It is shown in the below image

After creating the tooling axis we have to publish the tooling axis and the class-A surface for ease of access.

After creation of the tooling axis we have to perform the draft analysis. For making draft analysis we need to give material mode

After entering into material mode we have to select the draft analysis from the insert dropdown analysis tab,in that draft analysis we have to select the compass icon shown on the Direction tab’s second icon and we have to place the compass from the screen and place it along the tooling axis.

The colour code shows the draft given on that surface, the colour codes shown here of green colour is above 3degree draft, here the draft given on the surface is 9degree so the part is shown in green colour.

Various views for the draft analysis is shown below,

top view of draft analysis

we can also measure the specific point's draft using the measure draft under running point

thus the draft analysis of the fan cover is done and manufacturability of the component is proved and tooling axis is also determined.