Pocket milling of composite fibre-reinforced polymer using industrial robot

In the recent decades, aerospace and automotive industry are replacing metal materials by carbon fibre-reinforced polymer (CFRP). The mechanical properties of CFRP materials are very attractive due to high mechanical strength and low weight. However, there are technological challenges in the machining process for this type of material. The anisotropy and inhomogeneity of the CFRP cause high wear of the cutting tool, spalling, delamination, fuzzing, fibre pull-out, matrix cracking, thermal degradation and resulting in poor quality of the part. In addition, the requirement for processes that are more flexible within a larger work area makes the use of industrial robot (IR) a promising alternative. The present work evaluated the performance of the IR regarding motion accuracy, which influences machining conditions of composites. The trimming in a pocket milling was carried out using the factional replication of the 3k factorial design, with three levels and three factors. The tool geometry, feed rate fz and spindle speed n were selected as input parameters. In order to evaluate the robotic machining performance, resultant cutting force Fr, surface and dimensional quality were selected as output parameters to be assessed. After obtaining the force results, equations were generated for each cutting tools and Response Surface Methodology (RSM) was applied. The results show that the use of IR is a promising alternative for the CFRP machining of large aeronautical components.