Week 8 - Challenge 2 - Base Bracket Design
DRAFT ANALYSIS
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 take reference point to create dummy tooling axis.
Now click intersection option and select class A surface and YZ plane to get intersecting line on the surface.Then we need to create reference lines in the profile using point to point option in order to create the bisecting line.
By creating bisecting line Tooling Axis is formed.
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.
Construction of B & C surfaces
As we know class A surface is outermost part of the component which gives the aesthetic looks, class B surface is the inner part of class A surface. It consists of supporting sections ,ribs, bosses etc. It is done by first extracting all portions of class A surface and then offsetting it.
In class C surface first two holes are done using exract and sweep option. Then the outer surface is extracted from class A surface and sweep option is used.
Both B & C surfaces are joined togather and then trimmed.
Once all the trimming is done solid model is created in part workbench using closed surface workbench.
