Prepare Semi-Unintelligent Parts with Suppression and Sculpt Wrapping29 Jun, 2011 By: Mark Flayler
IMAGINiT Tricks Tutorial: When Shrinkwrap doesn't provide enough control for your needs, other Autodesk Inventor tools can simplify your designs for downstream use.
Editor's note: This tutorial courtesy of IMAGINiT Technologies.
When a design is to be sent out for vendor or client use, it is often necessary to remove some design information, but also to retain critical information for the downstream users. In the end, we want a part that is easy for our clients to use, but difficult for them to have another manufacturer replicate or reverse-engineer. Sometimes this is unavoidable with your particular products, but for parts with complex core/cavity systems like hydraulics manifolds or castings, it is definitely something to strive for. A fair balance must be struck between the outside world and your engineering department on what is critical and what is not.
When Autodesk Inventor introduced Shrinkwrap in 2010, many users got the idea that this was the be-all and end-all simplification tool for this need. After looking at Shrinkwrap, however, it becomes apparent that this is an all-or-nothing scenario, where very little control is given over specific hole-patching and how much of the hole depth is patched. Also, control for removing other outside geometry is not available; Shrinkwrap simply removes interior geometry.
Once the design criteria have been examined and agreed upon, the simplification process can begin. In this example (below left), we have determined that the half-moon–shaped cut on the bottom of this part, as well as the location of two of the mounting holes (in red, below right), are too design-sensitive to be examined by third parties directly through the model.
Since the two mounting holes are the same size, the Shrinkwrap command will not allow these holes to be filled without filling the other two holes as well. The other two holes are important to the client for locational reference, and must be visualized when exported. To help in translation file size, we have also decided to turn off the non-critical fillets of the model.
This example becomes rather easy, considering the features we need to turn off are ones we created as separate features during the design process. Let's take it a step further and create a parametric rule that aids us in the suppression of the desired feature so we can come back to this model and easily go between the two. We'll start by suppressing the required features in the model that were created during the design process. (Note: If you are using Suppression, it is important to avoid too many parent–child dependencies, as the suppression of one feature can cause the failure of another.)
Next, launch the Parameters window, add a new User Parameter called SuppressionControl, and set the value to 1 or 0. In the comment area, state what 1 or 0 will accomplish (e.g., 1=SuppressionOn; 0=Suppression Off).
Once the parameter is set, go to the Model browser, right-click on each suppressed feature, and select properties from the Feature Properties menu. Choose the Suppress If option and change the controls so that the suppression will take place based on the parameter values previously entered (use the check boxes and pull-down lists to select, for example, Suppress If SuppressionControl = 1).
From here on out, simply go to the Parameters box to change the suppression control, and export the file to a neutral format for vendor or client use.
On the more complex occasion where the geometry has too many dependencies, derived bodies, or features to suppress — such as in the example below — the Sculpt command works better for the simplification process.
To aid us in this simplification we will employ other commands, such as Boundary Patch. Our goal is to create a watertight boundary with the latter so that Sculpt will backfill material into the solid, removing our engineering data.
Start using Boundary Patch to close up boundaries that will help to fill the void inside the complex geometry. With this extra simplification control for our geometry available, we have more options for what we do and do not want to show the consumers of our data. In this instance, we want to be able to show individual SAE port locations for the clients to use in their model and to plumb up their fittings and hoses, whereas Shrinkwrap would close holes based on very limited criteria.
With the boundaries patched, start the Sculpt tool and select all the recently created patches.
If it's done correctly and the void is closed, a preview will verify this result.
Select OK, then examine the new sculpted and correctly simplified model.
As you can see, the SAE ports are still visible, as are the numerous mounting holes that will be required by the consumer for their designs, while keeping your intellectual property intact.
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