A SEM and EDS insight into the BUL and BUE differences in the turning processes of AA2024 Al-Cu alloy

When a Built-Up Edge (BUE) and a Built-Up Layer (BUL) are formed on the rake face of a tool, the surface finishing of the workpiece, the tool geometry and other output parameters can be affected. Till a few years ago both effects were considered as two forms of the same phenomenon. More recently, some authors have established differences between BUL and BUE, those related to thickness. The mechanism of BUL and BUE formation is not taken into account by these authors. This work reports on the results of a study using the SEM and EDS of the microstructural features of BUL and BUE formed over TiN turning inserts in machining of an Al-Cu alloy. The results obtained in this study have allowed the establishment of a first hypothesis about the differences between the mechanisms of BUL and BUE formation. (C) 2001 Elsevier Science Ltd. All rights reserved.