Part Modeling > Engineering Features > Shell > About the Shell Feature
About the Shell Feature
The Shell feature hollows out the inside of the solid, leaving a shell of a specified wall thickness. It lets you specify a surface or surfaces that you want to remove from the shell. If you do not select a surface to remove, a "closed" shell is created, with the whole inside of the part hollowed out and no access to the hollow. In this case, you can later add the necessary cuts or holes to achieve proper geometry. If you flip the thickness side (for example, by entering a negative value, or by clicking on the Shell tab), the shell thickness is added to the outside of the part.
When defining a shell, you can also select surfaces where you want to assign a different thickness. You can specify independent thickness values for each such surface. However, you cannot enter negative thickness values, or flip the thickness side, for these surfaces. The thickness side is determined by the default thickness of the shell.
The Shell feature allows you to select the adjacent tangent surfaces. This enables you to remove or offset (independently or with different thickness) the surfaces which are tangent to their neighboring surface at one or more boundaries. At the tangent edge, where the separation of the shell offset occurs, a normal capping surface is constructed to close the gap.
You can also exclude one or more surfaces from being shelled by specifying the surfaces in the Exclude Surface collector. This process is called partial shelling. You can also exclude surfaces with adjacent tangent surfaces. To exclude more than one surface, hold down the CTRL key while selecting the surfaces. The system cannot shell material that is normal to the surfaces specified in the Excluded surfaces collector.
When the shell is created, all the features that were added to the solid before you created the Shell feature are hollowed out. Therefore, the order of feature creation is very important when you use Shell (see example).
To access the Shell feature, click Model > Shell.