Product analysis automation for digital MRO based on intelligent 3D data acquisition

3D data acquisition technologies are increasingly used in the area of maintenance, repair and overhaul (MRO) of long-life technical systems and industrial plants. Application fields are measuring, reengineering and reproduction of disassembled parts. Fraunhofer IPK is developing a reverse engineering process for provision of 3D product models based on 3D scans of complete assemblies to save disassembly time and to support change management and reengineering tasks. This paper depicts results of IPK's data processing approaches for automated separation and identification of single parts in 3D assembly scans as well as for mapping of assembly structures in product data management systems. The major requirement was to automatically derive a product structure for assembly models as typically used in CAD or PDM systems. This structure can either consist of parts which were retrieved from a data base with solution element 2 or generated by conventional reverse engineering. To generate a contact graph for part relations in an assembly and its sub-assemblies a combination of different principles was realized in a software prototype and tested. This prototype loads the CAD parts of an assembly in one batch, before the user starts the structure generation process either fully automated or semi-automated by setting a threshold value for determining number of main assemblies of a product. Firstly, adjacent surfaces are identified by neighborhood analysis including contact surfaces and cutting volumes to derive a 2D contact graph. Secondly, the Girvan-Newman algorithm was applied to partition sub-graphs. Thirdly, a top down iteration for partitioning completed the product structure. Manual modification of structure nodes is possible in order to address a specific design intent or way of structuring the (sub-) assemblies. Finally, the CAD structure could be exported in an XML-based format for PDM data exchange. The file references all 3D models of the assembly's parts. For instance with SPLM Teamcenter, assembly import is possible with out-of-the-box functionality.