Signal analysis revealed that the maximum peak current decreases substantially with increasing FTL.
A second obstacle is the sensitivity of the tool to orthogonal forces such as adhesion.
Experiments show that even when using tungsten carbide tools, from a FTL aspect ratio of more than 50 onwards, bore diameter and machining time increase exponentially.
Therefore, adapted machine tool setups have to be designed, allowing for a minimum FTL while still enabling coaxial vibration coupling.
One approach is the use of membrane-shaped piezoceramic actuators.
The design for such setup is currently taking place.