Calibration, referencing and tolerance management

Automatic positioning, shape correction and position correction

Automated machining and assembly of lightweight structures, in accordance with the required manufacturing tolerances, requires high-precision measuring and positioning methods that are individually adapted to the respective component geometry and manufacturing situation. Flexurally weak components – up to XXL formats – which are to be regarded as unique specimens due to the geometric deviations caused by manufacturing, must be automatically positioned and their shape and position corrected. The researchers at Fraunhofer IFAM control and monitor this with 3D geometry measurements which are also automated, for example using coupled laser-optical geometry acquisition methods.

Adaptive path control and absolute positioning accuracy

Interlocking hardware and software solutions are required to automate processes on large lightweight structures. Unavoidable deviations of the components from the nominal geometry require adaptive path guidance. Software calibration increases the absolute positioning accuracy of sensor-guided actuators – e. g. industrial robots – into the range of repeatability. In combination with a CAD-CAM coupling, the required precision for component-adaptive assembly and machining is thus achieved.

Each process chain requires an individual automation solution. To this end, Fraunhofer IFAM not only provides technology modules, but also combines and integrates them with commercially available components such as robots, controllers, and various process-specific end effectors to create a prototypical overall system.

Automated tolerance management: precision through sensor technology

When carrying out assembly processes on large components with low inherent rigidity, precision can be achieved in various ways. Up to now, a component is usually clamped into frame structures that are built with high accuracy and that are very rigid. The disadvantage of this solution is that it is very expensive and a frame structure must be kept in stock for each geometry. The experts at Fraunhofer IFAM have therefore developed flexible component fixtures and clamping fields which adapt precisely to the geometry of different types of components, thus enabling active, automated tolerance management. Self-propelled designs also make it possible to save further non-productive time to a considerable extent by avoiding set-up and finishing operations as well as repeated geometry measurements in the process line.