...
The Interface Tool is combining the creation of Non-Design Spaces and Machining Allowances into one Tool. All functional faces (boundary condition application regions, stopping points, etc.) are selected and individual values can be applied to each surface region to create the according Non-Design Space and Machining Allowance.
...
The Offset Distance defines how much material at the front and back surface will also be defined as interface regions. In case of a sleeve for a screw not only the inner cylinder is important but also the front face where the screw head is connected to the part. This front face is also a functional surface and needs to be applied with an Machining Allowance.
...
Note: When the interface thickness ≥ offset distance then the interface volume will be hidden in GUI due to a current limitation. The optimization will still consider the entered values and the Print Geometry will consider the entered Machining Allowance value.
...