Characterisation of friction properties between a laminated carbon fibres reinforced polymer and a monocrystalline diamond under dry or lubricated conditions

The machining of carbon fibre reinforced polymer (CFRP) is a hot topic for the aircraft industry. Such materials are considered as difficult to cut materials due to their heterogeneity and presence of hard fibres. In this context, a lot of finite element models have been developed in order to understand their material removal mechanisms. Among the scientific issues faced by these works, the identification of friction coefficients between CFRP and cutting tool materials remains unanswered. So, this paper aims to characterize the friction properties between composite and cutting tool materials. For instance, the paper focuses on the context of a laminated CFRP machined with a monocrystalline diamond tool under dry or under lubricated conditions. The specific tribological conditions during machining of such heterogeneous materials are discussed in the paper, especially the configuration of the tribosystem (‘opened tribosystem’) and the orientation of laminates and fibres during sliding. The great lack of friction coefficient is mainly due to the absence of relevant tribometers simulating the tribological conditions occurring in cutting. This paper presents the development of a new tribometer designed to simulate conditions corresponding to machining of CFRP materials. It provides quantitative values of friction coefficient depending on several key parameters. A range of sliding velocities and contact pressures has been tested. The influence of layers orientation and cutting fluids has also been investigated. It has been shown that friction coefficients are very low (∼0.06) in dry regime. Friction coefficient is not sensitive to contact pressure nor to sliding velocity. Additionally this works has revealed that a cutting fluid leads to a significant decrease in friction coefficients (∼0.02), which corresponds to a friction less situation.