Numerical Cutting Simulation and Experimental Investigations on Determining the Minimum Uncut Chip Thickness of PTFE

Polytetrafluoroethylene (PTFE) has become an essential material in the manufacturing of critical flow-control components in various industries. These components require high surface quality and micron-level machining dimensions. The study of the minimum uncut chip thickness (MUCT) presents an opportunity to enhance the machining precision of PTFE. The objective of the research is to determine the MUCT of PTFE by employing finite element (FE) cutting simulation and orthogonal cutting experiments. Initially, the two-dimensional orthogonal FE cutting models, with varying parameters of cutting depth (30-80 mu m) and cutting speed (5000 mm/min), utilizing the Johnson-Cook (J-C) constitutive model has been applied for simulating the MUCT of PTFE. The parameters of the J-C constitutive model have been determined through quasi-static tension tests (Strain rates: 0.001 s-1-0.1 s-1, Temperature: 24 degrees C) and the split Hopkinson bar (SHPB) tests (Strain rates: 500 s-1-3000 s-1, Temperature: 24-100 degrees C). Subsequently, the orthogonal cutting experiments corresponding to the FE simulation are designed and performed. The cutting force, cutting chip, and machined surface morphology are analyzed to assess the precision of the established FE model and determine the MUCT of PTFE. It was concluded that the numerical results are in good agreement with the experimental results, with a minimum relative error of 0.885% in cutting force and 2.03% in the axial ratio of chip curvature. And the MUCT for PTFE was determined to be 70 mu m in this study, in the case of rake angle, flank angle, and tool edge radius of the cutting tool are 0 degrees, 6 degrees, and 40 mu m, respectively. It has been indicated that the properties and flow direction of the removed workpiece material play a significant role in chip formation under the influence of extrusion and friction in the workpiece-tool-chip contact area. These results offer a theoretical foundation for enhancing the machining precision of PTFE.