 | 2010 |
Abstract:
Connecting aluminium extrusions with other structural elements via screw-coupling is often challenging due to the small wall thickness of the profile sections. The manufacturing technique of flow drilling combined with a subsequent threading operation offers a possibility to cope with this difficulty. With flow-drilled holes, more threads can be integrated into a thin-walled section due to a bushing formed from the displaced material. During the machining operation, high process-related mechanical and thermal loads act on the extrusion, and finally affect the machining results. To evaluate correlations between the process parameters, the geometric form of the machining results and the subsurface microstructure of the material, experimental investigations have been conducted using extruded aluminium wrought alloy components. To evaluate the geometric form and to examine the post-process subsurface microstructure of the material, longitudinal sections of flow-drilled holes are analyzed. To quantify the benefits of flow drilling, threads were produced by forming process, tapping, and thread milling, separately, in ordinary holes and in flow-drilled bushings for tensile tests. The ultimate tensile strength of the threads is used as a quality benchmark for the overall machining results.