Investigating surface finish, burr formation, and tool wear during machining of 3D printed carbon fiber reinforced polymer composite. (August 2020) - Cococcetta, Nicholas M.
Abstract: Carbon fiber reinforced polymer (CFRP) composites are taking place as the most commonly used material in automotive and aerospace applications due to their superior strength-to- weight ratio, corrosion resistant exterior, and high performance under extreme conditions. Additive manufacturing or three-dimensional (3D) printing of CFRP composites is rising in popularity due to the ability to manufacture complex shapes and alter the fiber orientation of the material. However, difficult-to predict-microstructures along with non-uniform fiber dimensions plague researchers from predicting the response of the material. The objective of this research aims to investigate the machinability of 3D printed CFRP composites with different matrix arrangements, while varying machining process parameters and lubricating conditions. When testing the machinability of each material sample, one edge and slot milling operation was performed at the same feed rate, followed by an additional slot milling operation with an increased feed rate. These tests were run on varying fiber orientations, to observe how the machining response changes with differing matrix layout. After experimenting with different machining parameters and microstructural compositions, post-process machining was found to improve the quality of the surface finish when machining 3D printed CFRP composites. In all three samples, light microscope images showed a surface with less imperfections and protrusions, signifying a more even and applicable surface finish. In addition to the improved surface finish, machining results in burr formation, that requires additional efforts to clean the surface allowing use in end application. To reduce the degree of burr formation and improve machining results from dry machining, experiments were re-run using minimum quantity lubrication (MQL) techniques. Both the surface finish and tool wear were found to improve under MQL conditions. The burr formation was also significantly reduced, when MQL were used in the machining of CFRP composites.