Additive manufacturing processes are no longer prototypes - they're on their way to establishing themselves in industrial production. Where injection moulding is the preferred choice for processing large quantities of plastics with high quality requirements, additive manufacturing is suited for efficient production of individual parts and small batch production. In the meantime, all business sectors from the automotive and consumer to medical technology can take advantage of this. It is possible to build up various different functional components layer by layer with tiny plastic droplets. Piezo actuators are the driving force and therefore play an important role in producing tiny droplets.
The variety of materials and applications in plastics processing is increasing: a trend recognised early by machine engineering specialists Arburg. In addition to classical injection moulding for this growing market, Arburg has developed another industrial process: Arburg Plastic Freeforming, a so-called freeformer that allows a large amount of design freedom and material diversity, and also realises part-geometries that normally could not be formed with injection moulding.
The freeformer is an additive manufacturing system for producing functional plastic components from qualified standard granulate, individually or in small volume batches. It is equipped with two discharge units by default. This allows the combination of different materials or the realisation of complex geometries. The installation space has room for parts that measure up to 154×134×230mm.
The functional principle of the freeformer is easy to understand. First, the 3D CAD data for the component is prepared for the machine using special software. A functional component is then made from the layered geometries without tools or reworking. The granulate is filled into the machine and a heated plasticising cylinder with a special screw generates a homogenous molten mass out of this for the discharge unit. The patented nozzle shutter with high-frequency piezo technology enables a fast opening and closing motion, and generates around 200 plastic droplets every second at a pressure of up to 500 bar. The component is ready to use as soon as it comes out of the machine.
The central process of additive manufacturing is the generation of the droplets at the nozzle of the discharge unit. A piezo actuator is used to clock the nozzle shutter because it provides the necessary high dynamics and accuracy for the material discharge. In addition to this accuracy and dynamics, the PICMA actuator from Physik Instrumente that is used for clocking the nozzle shutter has features that make it perfect for industrial additive manufacturing. No other valve technology offers such a fast response time at a comparable size. PICMA actuators surpass conventional, polymer-coated piezo actuators in performance and lifetime because of their all-ceramic insulation. In the meantime, the freeformer has proved itself in various different applications in the automotive and consumer sectors as well as electronics manufacturing and medicine.
