  Turning is the most commonly available and least expensive machining
operation, in terms of both machine-hour rates and tool insert prices. A
practical CNC process planner has to maximize the utilization of turning, not
only to attain precision requirements for turnable surfaces, but also to
minimize the machining cost, while non-turnable features can be left for other
processes such as milling. Most existing methods rely on separation of surface
features and lack guarantees when analyzing complex parts with interacting
features. In a previous study, we demonstrated successful implementation of a
feature-free milling process planner based on configuration space methods used
for spatial reasoning and AI search for planning. This paper extends the
feature-free method to include turning process planning. It opens up the
opportunity for seamless integration of turning actions into a mill-turn
process planner that can handle arbitrarily complex shapes with or without a
priori knowledge of feature semantics.
