Week 8 - Challenge 4 - Coin Holder Design

CONSTRUCTION and DRAFT ANALYSIS of COIN HOLDER

Draft analysis technique is used to analyze whether our part model created in CAD is manufacturable or not. The part should get easily removed from the mould or die. No part can be ejected from the tool if it is having straight 90 degree angle from its base surface. A small draft angle is provided to each and every area of the component and we are providing a direction in which components should eject in order to easily remove the component from the tool.

Draft Angle is the amount of taper given to the molded parts perpendicular to the parting line. As the plastic cools it shrinks and sticks to the mould surface and therefore need draft angle while ejecting, and to avoid damage. Normal draft angle is 3 degree. Increasing draft value will increase manufacturing cost.

TOOLING AXIS

In order to perform analysis, we need to create tooling axis and in order to do that we need to check class A surface first. We need to check whether all the surfaces are closed or not using boundary option. Once inspection is complete, we need to create separate geometrical set for tooling axis. We need to choose the axis in such a way that all the pockets, holes, sections etc. should get covered. For example, once inspection is completed, we concluded that Z axis is the tooling axis. Now we first extract the base surface from class A surface.We than create a reference point at the centre of the surface. Now insert an axis system at that point. Create a line at that point. This line is our MAIN TOOLING AXIS.

DRAFT ANALYSIS

Now we need to check whether material mode of class A surface is in customize view parameters. Now go to Insert – Analysis - Feature draft analysis. Select the compass mode and drag the compass to the tooling axis of class A surface . Now select the surface to activate the surface and lock it using lock button. You can also do analysis during running point and move mouse all over the surface to check degree and draft angle. You can do analysis on full scale mode or quick scale mode. The color change shows change in draft angle.

After draft analysis you can see that the surface also has negative draft. This is because the side walls of the surface is either 0 degree or exactly 90 degree to the base surface, because of which during manufacturing the side walls of the component might get damaged during part ejection. The solution is to recommend the class A surface designer to give a minimum draft angle of 3 degree to all the walls.

Class B creation

First we extract the side walls part of class B surface,then extrapolate it and trim togather.

Next we extract base from class A surface,extrapolate it and trimmed togather.

Next we extract the top walls from class A surface ,extrapolate it and trim togather.

Now outer flange is extracted from class A surface ,extrapolated anf offseted.

Now trim all the surfaces to create one full component.

Class C surface creation

Now we extract outer boundary of outer flange and use sweep option to create the surface.

Now both the surfaces are joined togather and trimmed.

Now to do the cutout part ,we extract the surface from class A surface and extract boundary of cutout. Now use sweep option to form the surface and trim it .

Now give the required fillet to all the edges.

Now go to part workbench and use close surface option to form solid body.