Drilling of Thick Composite Structures State of the Art

Aeronautic structure parts are increasingly manufactured using long fiber composite materials. A modification of the assembly hole drilling process is necessary to adapt it to the specific qualities of these materials. At the entry and at the exit of the part, delaminations are generated by the use of a conventional twist drill. The delamination of the composite materials is related directly to the thrust force (F_Z) of the tool. So, it is interesting to study the drilling of thick plates for the composite assemblies. In this paper, several types of tools will be examined and an analytic model will be developed for the calculation of the critical thrust force (F_Z) in drilling with a conventional twist drill. Finally, the present study can be used to choose the optimal tool that provokes the minimum of delamination in composite materials drilling.