Influence of Duplex- tool coatings on the thermomechanical tribological properties during friction spinning of AW 6060 and the generation of a numerical simulation of the friction spinning process

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Based on the first funding period, this follow-up project is concerned with the analysis of the friction-pressing process in more detail with regard to the friction and the adhesion processes during the forming of AW 6060. In this context, duplex coating systems are developed for the friction-spinning tools, which aim to optimize the heat flow in the tool-workpiece system and to minimize tool wear and increase the surface quality of the workpieces. Thus, a deeper understanding of the adhesion mechanisms of TiBN-PVD thin layers on oxide-ceramic thermal barrier coatings (TBC) is generated through the application of adhesion-promoting metallic interlayers. The interactions of the TiBN top layer on the friction and adhesion properties during the friction-spinning process are then analyzed. The duplex coating integrates atmospheric plasma sprayed Al2O3 or ZrO2-8Y2O3 TBCs and a metallization of their surfaces with NiCr, Ti or Cr using cold gas spraying. The aim of the metallization is to completely cover the surface-near pores of the TBC and thus to reduce the roughness in order to achieve a near-net-shape deposition of TiBN by means of PVD. The surface roughness of the tool is correlated particularly with the adhesive wear during the forming of AW 6060.Furthermore, approaches will be analyzed to optimize the tool performance. These approaches include the application of the developed duplex coatings, varying the contact area size in addition to applying grooves and lubrication. Consequently, process strategies are to be derived to optimize the heat flow and to reduce the adhesive wear.The results of the first funding period confirmed the dependency of friction especially on temperature and relative velocity. Furthermore, is friction dependent on normal stress. Due to the fact that friction spinning involves high temperatures, relative velocities and normal pressure values, the target of the second funding period is to characterize friction under real process conditions to obtain reliable results. For this purpose, an experimental setup will be prepared, in which a compression test is integrated in the friction-spinning setup, whereby a tool plate moves onto the rotating AW 6060 tube and initiates plastic deformation. The normal forces are to be measured directly whereas the shear forces will be calculated from torque measurements. The obtained forces will then be used to gain a solid understanding of the friction in this process and to derive representable friction model for friction-spinning. The friction values obtained will consequently be integrated in the thermo-mechanical FEM-simulation model to depict the friction spinning process. The simulation model is then validated with experimental values in terms of temperature, force and geometric features.