Face parts may sometimes appear to be upside down or inside out. This means that the positive and negative face normals are not in the correct orientation for your design.
The face coloring will show this; the positive side has a lighter turquoise shade than the negative side (as its default color). To convert face parts into a solid part, all positive face normals must point outward.
The Flip function allows you to switch the positive side with the negative side. You can flip either complete face parts or single faces.
In some cases you may also want to reverse the face sense. The face sense defines which side of a face edge is the material side. For example, when importing a single face with a hole you may get the hole as a face, instead of its surroundings. The In/Out option allows you to correct this in both directions.
The figure shows a sphere with a circular hole being flipped using the In/Out option.
Do not flip correct parts; this may corrupt the part.
To flip a face,
1. Click 3D Geometry and then, in the 3D Surface Tools group, click Flip Faces. The Flip Orientation dialog box opens.
Flip Faces. The Flip Orientation dialog box opens.
to complete the operation.