Cutting Process Tribometer Experiments for Evaluation of Friction Coefficient close to a CFRP Machining Operation

Abstract

Finishing operations of Carbon Fibre Reinforced Polymers (CFRP), such as drilling or milling are known to generate heavy tool wear. Consequently, ultra-hard cutting materials like diamond-coated carbide tools or PCD-tools are utilised. To further improve the lifetime of these tools, it is recommended to adjust the tool geometry, process parameters and coating to the relevant application. Usually, the process optimisations base on knowledge from fundamental experiments in similar materials or rarely on tool wear modelling. To improve suitable force and tool wear models, the friction coefficients between tool and workpiece under realistic conditions are required. To address the lack of friction coefficient at the tool/workpiece interface, a cutting process tribometer (CP-T) is utilised. This tribometer enables for friction measurements between diamond-coated cemented carbide pins and freshly generated CFRP surfaces downstream of a orthogonal cutting process. The tribological conditions in the measurement setup (e.g. velocity, pressure and presence of loose particles) are very similar to those occurring at the tool/workpiece interface during the cutting process. It is shown that the magnitude of friction coefficient as well as the influence of the fibre orientation is much lower compared to results of pin-on-disk tribometer (POD-T) experiments. This measurement data is of high relevance for machining force and wear modelling as well as cutting process optimisation.