Fig. suggests that for CF/epoxy, the improvement of MRR can only be achieved by simultaneously increasing the thrust force and Fda. This is however, at the price of compromised hole quality. In contrast, for CF/PEKK, the trade-off between the objectives is more complex. To better reveal the trade-off as well as the correlation between design variables and objectives, self-organizing map (SOM) is deployed for this work. SOM was previously employed in optimization studies including composite curing , aerostructure design and social science . In this work, SOM is constructed for the first time in the context of composite machining to visuallize the complex interaction between drilling parameters and drilling performance, see Fig. and Fig. .