This paper describes the interdependence of additive and subtractive manufacturing processes using the production of test components made from S Al 5356. To achieve the best possible part accuracy and a preferably small wall thickness already within the additive process, a closed loop process control was developed and applied. Subsequent machining processes were nonetheless required to give the components their final shape, but the amount of material in need of removal was minimised. The effort of minimising material removal strongly depended on the initial state of the component (wall thickness, wall thickness constancy, microstructure of the material and others) which was determined by the additive process. For this reason, knowledge of the correlations between generative parameters and component properties, as well as of the interdependency between the additive process and the subsequent machining process to tune the former to the latter was essential. To ascertain this behaviour, a suitable test part was designed to perform both additive processes using laser metal wire deposition with a closed loop control of the track height and subtractive processes using external and internal longitudinal turning with varied parameters. The so manufactured test parts were then used to qualify the material deposition and turning process by criteria like shape accuracy and surface quality.

This paper reports on a simulation framework capable of predicting the outcomes of the friction stir welding process. Numerical tool development becomes directly possible without the need for previous calibration to welding experiments. The predictive power of the framework is demonstrated by a case study for numerical tool development and validated experimentally. Different tool geometries with high levels of detail and active material flow features are investigated, and their effect on the process outcomes is quantified. The simulation framework is found to be able to predict forces, material flow, temperature fields, weld formation and welding defects a priori, in detail and precisely. This applies to the outer appearance of the weld as well as the location, shape, and size of inner welding defects. Causes for defects can be identified, analyzed and remedied. Compared to the validation experiment, the simulation showed a slight overestimation of the process impact in the case study. Since the framework relies strictly on analytically describable physics, the efforts for modeling the process are moderate considering the precision of the results.

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The Friction Stir Welding (FSW) process depends entirely upon mechanical contact between the tool and the workpiece. As a result of this, all process phenomena and process outcomes such as weld geometry and mechanical properties are governed by FSW’s frictional system. The following work characterizes this system with a focus on process initialization, heat input and material flow. For this purpose, an experimental program for the isolated investigation of the frictional system was carried out. Short-term effects such as contact initiation, run-in behavior and frictional transitions are considered as well as the influences of process parameters and geometry. The system and its behavior are analyzed quantitatively and qualitatively by experiments altering the normal pressure, relative velocity, and tool geometry. The experiments demonstrate a self-similar behavior of the process, including an important wear transition which initiates the material flow, and a subsequent equilibrium of forces, heat balance, and temperatures. The interaction between the tool and the welded material is described, as is the link between the frictional interface and material flow initialization. Based on these findings, recommendations are provided for process optimization and tool design.