Holistic development and characterization of an efficient manufacturing of detachable joints for aluminium and magnesium lightweight materials

• Applicants: Professor Dr.-Ing. Dirk Biermann; Professor Dr.-Ing. Frank Walther
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering ; Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258976435

Metallic lightweight materials are used for enhancing the dynamic range, resource optimization andemission reduction in many fields of traffic engineering. Aluminum components are manufactured by means of welded, adhesive and screw joints. Friction drilling, as a forming process with subsequent manufacturing of threads, offers the opportunity to produce an internal thread in lightweight profiles with a usable thread depth larger than the profile thickness, making use of local material expansion. Moreover, the direct manufacturing offers a huge potential for time and cost saving in comparison to conventional thread machining.In this research project a reliable friction drilling concept for aluminium and magnesium alloys AlSi10Mg and AZ91 shall be developed to generate detachable joints by means of thread forming. Thread forming offers the advantage that it is a non-cutting process and leads to work hardening in the border area compared with tapping. An advanced friction drilling process will be used, where the work piece is front-end expanded. The operational range is distinctly extended and joinings for profile connections can be realized without additional design features. Test methods shall be applied by means of application-optimized measurement sensor technology to characterize the quasistatic and cyclic material behavior of internal threads with an appropriate amount of tested specimens. Selected process-relevant parameters are varied during the manufacturing and comparatively evaluated with the mechanical characterization methods. The feedback of the results allows a resource optimized and efficient thread machining.The aim of the proposed research project includes the holistic development, characterization and optimization of an innovative friction drilling process with subsequent thread manufacturing in aluminium and magnesium alloys. Especially the model based correlations of the process-structure-property-relations are to be investigated. The process related geometrical and microstructural properties of internal threads are correlated with the mechanical properties, whereby a structure-based analysis of the damage mechanisms leads to a comprehension of an optimal process parameter designing.

• DFG Programme: Research Grants