For generating the droplets, we decided to use a piezo actuator for clocking the nozzle shutter because this provides the necessary high dynamics and accuracy for the material discharge.
Properties of the Piezo Actuator
In addition to accuracy and dynamics, the PICMA® actuator that is used for clocking the nozzle shutter during the APF process, has a number of other features that predestine it for use in industrial additive manufacturing. The actuator designed to customer specifications has travel ranges up to 90 µm with subnanometer resolution, can be pressure-loaded to 3,000 N and its microsecond response time makes it exceptionally fast. No other valve technology offers such a fast response time at a comparable size.
Furthermore, PICMA® actuators surpass conventional, polymer-coated piezo actuators in performance and lifetime because of their all-ceramic insulation. The ceramic insulation layer protects the monolithic piezoceramic block against humidity, and failure due to increased leakage current, and therefore achieves high motion cycles under extreme ambient conditions. The monolithic structure also causes a high resonant frequency, which is the reason why these actuators are ideally suited to highly dynamic applications.