Using Shrink-wraps to Calculate Container Volumes

Calculate container volumes in Autodesk Inventor

In a previous life, I used to design rotationally moulded fuel tanks for Automotive OEM’s. A big part of the job was squeezing as much extra capacity into the tanks.

Usually, I would calculate the volume before shelling the model, and then again after shelling the model. The difference between these 2 numbers is the theoretical volume of the model.

In this example, I am working with a 3rd party CAD file from Grabcad, so I am working with a dumb solid, which means no control over the thickness of the shell.

The first step is to create a new assembly (If you are not already in one), and to create a Shrinkwrap substitute.

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Ensure that you remove all Holes and Pockets, but leave the settings for Fillets and Chamfers set to “None”. This will make create a filled solid.

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Next we need to open the shrinkwrap substitute, simply right click on the model and select “Open”

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With the filled solid model open, the next step is to insert the shelled model as a “Derive”

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This will overlay the shell over the solid filled model, as shown below.

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The last step is to remove the shell from the filled solid. To do this, we are going to use the “Combine” tool. The “Base” is the filled solid, the “Tool Body” is the shell.

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The result is the maximum theoretical volume. You may wish to remove some of the volume from the top of this model to adjust for real world filling etc.

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Finally check the iProperties to check see the volume.

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