In the past, I had a similar project, and the approach I took was as follows:
In Powermill, the static model represents your cutting blade. Your machined product acts as a form tool with the desired shape (in my case, I needed to create a specific contour in the machined part).
In Powermill, draw a horizontal pattern line starting from the edge of the static blade. Then, utilize the "Pattern Finishing" strategy with the "drop" option enabled. This will calculate the toolpath, starting from the center of the rotating part, intersecting with the blade's edge, and dropping down to contour around it. You can set the Z minimum by simply limiting it with block limiting. As it descends, it will machine the desired shape for the rotating part, following the form tool's shape.
Now, with just one finishing toolpath line, you can clone this toolpath and adjust the thickness to create multiple passes.
