Remove lines between faces

If faces are completely tangent (and there are different degrees of tangency, just because you set your boundary surface end condition to "tangent" doesn't mean it is "perfectly" tangent) and you have the parameter in Tools>Options>System Options>Display/Selection>Part/Asembly tangent edge display set to "removed", then the edges will not show.

If you are taking the part into a drawing, and you want the edges to be hidden, you can either:

recreate the transition between the two surfaces to make it perfectly tangent (good luck!)

or more realistically, you can just use the tool in the Line Format toolbar called "hide edge". You will have to do this by hand for every edge in every drawing view.

Chris,
As a general rule, any discrete edges or vertices between edges will propagate into adjacent faces. Our Knit command does automatically eliminate edges (eliminate topology) but if you still have edges, look at the curves or edges that exist that could be causing them. A good tool to use to simplify your surfaces is to use "Fit Spline on the 2D and 3D sketch geometry that initially creates your surfaces - i.e. if you have a profile or curve for Loft, Sweep or Boundary that is made up of a series of lines and arcs, the vertices (connection points) between the lines and arcs will propagate into the surface. Some of our surfacing features have an option called "merge tangent faces" make sure this is on if you want to simplify your geometry. Delete face and Replace face can also be used, in some situations, to "clean up" unwanted faces within the topology of your part.

Chris,

Try this and see if it works for you.

INSERT>FACE>DELETE>Delete and Patch (under Options).