The tightness restriction is a variant of the demold manufacturing constraint with
the MID_PLANE
parameter set to AUTO_TIGHT
. The following
figure shows an example with the default casting restriction (MID_PLANE=AUTO
,
left) in comparison to the tightness restriction (MID_PLANE=AUTO_TIGHT
,
right):
The elements are removed in a similar way to the AUTO
option. This means
that the elements are removed in the pull direction or in the opposite direction. However, at
least one layer of elements will be present in the middle plane. The resulting "middle plane"
is not necessarily planar. It might be a curved surface.
The tightness is only checked within the restriction area. It is impossible to ensure a
tight connection to elements outside the restriction group in the area of the boundary.
The midplane thickness is controlled by the RADIUS
parameter (midplane
thickness = 2*RADIUS
). The radius should be at least the size of the average
element to ensure that a correct midplane can be found.