Under default conditions, a loft operation in Creo Elements/Direct Modeling generates edges between the vertices of each loft profile, and then incorporates them into the loft surface. These edges are created by default, irrespective of whether a smooth tangential transition occurs between adjacent curves in all profiles.

To add a loft,

A Smooth option in the Loft Add dialog box enables you to generate a lofted part with a smooth surface. When active, the smooth option prevents the creation of edges between adjacent faces which are connected by smooth tangential transitions in the profile. The vertices at these points are also removed from the resulting part.

During a loft operation, an edge is always created along the matchline between the loft profiles. Consequently, if you are using profiles which have a non-tangential transition at one vertex, you can minimize the number of edges on the resulting loft surface by directing the matchline between these vertices.

The figure compares two parts resulting from a loft operation made with the Smooth option cleared (A), and then with the Smooth option clicked (B). Line 1 is the matchline between the two loft profiles, and line 2 is an edge between two non-tangentially connected faces. The lines labeled 3 in part A represent edges on the surface of the lofted part that connect the vertices of the two loft profiles.

By clicking the Smooth option, you can prevent edges from being created between neighboring faces which have smooth tangential transitions between them. This option creates a smooth surface on the lofted part B. You will see that even with the smooth option active, an edge is always created along the matchline.

You can also use the Smooth option when removing material from a part using a loft.