Shell VS. Thicken

[CNSZU]

Hello,

My task is to create an outer plastic molded shell casing. Should I use the Shell command or the Thicken command? Also, there is another command, Sheets to solid assistant, which seems to be the Thicken command in disguise. People have said that Shell and Thicken create completely different topology, but I can't see any difference. The attached image compares the exact same shape using both commands. Can anyone give a visual example of how these two commands are different, and which command is most suitable for a plastic casing? Are there situations where one command would fail and the other one works? Thanks.

NX8 i7-3770K@4.3Ghz 16GB Quadro2000

 

[JohnRBaker]

The basic difference is that 'Thicken' creates a model where the 'edge' topology is normal to the face being thickened, where as will a Shell operation that would only occur in very special circumstances. To see what I mean, review the image below (and the attached file). What I have is basically the same shape, a 45° segement of an Arc rotated about an access. In one case (the Green body) I created a 'solid' of revolution and then performed a Shell operation. The other case (the Cyan body) I created a 'surface' of revolution and then performed a Thicken operation.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[CNSZU]

I see, for a "sheet"-type object there would be a difference, but if we limit the scope to enclosed volumes (hollow object), the result would be the same regardless if the operation is Shell or Thicken, right?

For example, a solid object with the Shell operation, compared with an enclosed sheet object with the Thicken operation.

NX8 i7-3770K@4.3Ghz 16GB Quadro2000

 

[JohnRBaker]

Topologically it might be the same, but if you edit the model, when it updates the feature behavior could be different depending on what the new geometry looks like. Generally speaking, it's better to learn how each function behaves and then pick the one that will always give you the result that you expect no matter how the original model is modified.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.