## 3 Results
### Synthesis: The generic Product Lifecycle Model (gPLC)
The synthesis of the gPLC is proven by application in three cases based on data acquired in collaborative research projects performed by the authors (see detailed comparison as a documentation of the selection of cases in Section 2). Figure 10 presents models visu  
Figure 8: Inner and outer multi-cycle relations inter-linked by information flow. Figure 9: Lateral view of the gPLC: differentiation between product class and instances. alizing case-based adoption with regard to product types, material flow and information flow. The line thickness describes the prioritization of material and information flow in each case. The RepAIR case combines various options of material and information flow regarding single metal part instances in operating aircrafts. The OptiAMix case is based on anticipation of material flow (dotted green lines) and information loops from aggregated product instances (thick grey arrows) into strategic planning and engineering phases. The SugarFab case is focused on resources in realization and information loops from the entire Product Creation process back to service and realization. Subjects of the RepAIR case are structural parts of aircrafts manufactured from metals. As an example, turbine blade brackets are selected due to their manufacturability in both conventional processes and Selective Laser Melting. Parts are engineered and certified by an Original Equipment Manufacturer (OEM) of aircrafts and produced later on by suppliers both for series production and spare parts production. In future, Additive Manufacturing (AM) will be a relevant technology for the production of spare parts, especially in order to reduce CO2 emissions in global supply chains. Spare parts are needed at MRO locations close to airports around the globe. By means of Remaining Useful Lifetime (RUL) estimation, predictive maintenance is enabled. RUL, in a basic version, is based on part life data derived from flight data, and in an extended version, from sensors detecting loads over time. Figure 10a presents the application of the gPLC to the RepAIR case. Product Creation is visualized by the red arrow, abstracting from different stakeholders (OEM, supplier). Service is provided either by MRO providers servicing the owner of an aircraft resp. of the turbine. Typically, parts are replaced by spare parts based on RUL at maintenance time. The disassembled part is checked and repaired/refurbished afterward either at the MRO service company or back in the production site. It can be brought back into the cycle either as single spare parts or assembled into products. Information circularity is based on life data (a) as a basis for the product and/or MRO process innovation at the OEM or the MRO provider [108], (b) as a starting point for product generation engineering at the OEM, (c) as data input for RUL calculations and (d) as a basis for decision support for stakeholders using the part in flight conditions (airline, MRO). The OptiAMix case attaches importance to strategic planning and engineering. The OptiAMix case is focused on an automotive rear wing holder. The part is optimized for AM, but economic considerations imply that manufacturing highly depends on lot sizes. This means that different production technologies might be most suitable in the  
Figure 10: Application cases of the gPLC resulting from collaborative research projects: (**a**) European project RepAIR focusing on Additive Manufacturing of turbine blade brackets in aeronautics; (**b**) German project OptiAMix focusing on multi-criteria decision support in innovation and engineering management; (**c**) digitalization in sugar fabrication (here entitled SugarFab) targeting continuous evolution of production based on data analytics. ramp-up phase, series production and spare parts production. For the latter, options vary between on-demand manufacturing by AM, which allows the decommissioning of assets and keeping the production line operating.