Influence of the edge quality to the water sorption of remote laser and mechanically cut carbon fibre reinforced polymer

The processing of carbon fibre reinforced polymers (CFRP) is complex due to the heterogeneous material structure and the hard and brittle fibres. For the creation of the final contour during component manufacture, the trimming of semi-finished products is necessary. For these processing steps, multiple cutting processes are available. Depending on the chosen process, the structure of the edges can show considerable differences [1]. Reference [2] proves that the surface condition of CFRP influences the diffusivity, maximum moisture content and concentration. The cutting edge forms part of the component surface. The aim of the present study is an evaluation of the influence of the cutting edge condition on the moisture uptake of CFRP. A systematic analysis of the water sorption behaviour of CFRP with edges generated with thermal remote laser and mechanical processing technologies was performed. Also, the effect of edge sealing was considered. Depending on the applied process, differences in the moisture uptake of CFRP could be shown. Several remote laser cut samples with a distinct heat-affected zone (HAZ) absorbed water rapidly. Thermally exposed fibre ends may form capillaries. By choosing suitable laser processing parameters or edge sealing, this effect could be avoided, resulting in inconspicuous water sorption behaviour.