Development of a clamping system with piezo-actuators for high-precision positioning and force control for micro-machining

Improving clamping accuracy and controlling workpiece deformation during micro-machining require adaptation of holding forces as to the cutting forces and workpiece geometry. The available devices have a position accuracy of + /- 1 µm, however with lower and limited precision and repeatability when re-clamping. The developed and presented high-precision system achieves two goals: accurate repositioning and force-controlled clamping of < 20 N. The system, described in the paper, with three independent linear piezo-electric actuators, is controlled by a position and force algorithm, combined with a camera and a pattern recognition algorithm to identify workpiece positions and to accomplish feedback control. It was shown that controlling holding forces, position, and motion of each clamping jaw, can allow secure and accurate repositioning with a repeatability of 2–3 µm for controlled deformation in micro-machining.