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Over the last few years, many aircraft production lines have seen their production rate increase. In some cases, to avoid bottlenecks in the assembly lines, the productivity of processes needs to be improved while keeping existing machine-tools. In this context, the case of drilling machine-tools tends to require particular attention, especially when multi-material parts are drilled. In such instances, the Vibration Assisted Drilling (VAD) process can be a way to improve productivity and reliability while keeping quality standards. This article presents a case of a drilling/countersinking process for stainless steel and titanium stack parts. Firstly, the article assesses the feasibility and benefits of using Vibration Assisted Drilling and Countersinking with the current cutting-tools. Secondly, it studies the consequences of introducing a new tool holder in the process, which combines the V.A.D. function, a new declutching function and the ability to control countersink depth.

Aircraft design has mainly changed in the past years, introducing new materials such as CFRP at a large scale. Even if this great change brought many advantages: weight, sustainability, reliability… it upset the way to produce basic parts and to assembly. A special difficulty lies in drilling multiple stacks made of different materials, i.e. metal (aluminum, titanium, stainless steel) + CFPR. Indeed, as the process has to drill through those stacks during a unique operation, cutting conditions and tool technologies are a compromise. As a consequence, tool life cycle, productivity and above all, hole quality are no longer optimum. Some materials, such as titanium requires low cutting speed and high feed rate whereas CFRP requires opposite trends. Moreover, heat generated by cutting metal (especially titanium) can damage CFRP when overheated metallic chips pass through.