Case Study 3.3: Active Fixtures for High Precision Positioning of Large Parts for the Windmill Sector

The fixtures are used to locate, clamp and support the workpiece during the manufacturing process. Their performance affects the results attending to the quality, cost and performance. Thus requirements like accuracy, reliability, short set-up time and cost-effectiveness are demanded for the fixtures. Within the INTEFIX project, the design of an active fixture is presented for the accurate positioning of a planet carrier with very strict requirements of tolerances and for an intelligent adjustment during the machining process when required. This device will allow the manufacturer to reduce the manual inspections, to automatize the adjustment tasks and to improve the machining process setup time. This will increase consequently the productivity and achieve the required accuracy and the required geometrical quality of the part. The development of the active fixturing focused mainly on the conception of a high precision actuator capable of moving the large part with the required tolerance. The active fixture was implemented into the machine and the obtained results proved that the proposed active fixture is able to centre the workpiece within the tolerance of 10 μm assuring the quality requirements.