1. Drilling with vibrations
Motivation
Experimental system
Drilling CFRP only
Drilling CFRP Al stack
U. Ben-Hanan
Drilling with vibrations

2. Drilling with vibrations
Motivation
Better hole quality
Less force
Z. Linbo et al. / Composites
More papers about drilling with low frequency vibrations can be found in the references page.
Longer tool life
S. Arul et al. / International Journal of Machine Tools & Manufacture
Drilling with vibrations

3. Drilling with vibrations
Processing CFRP
Maximum thrust force that can be applied without causing delamination
This equation was developed by Ho-Cheng & Dharan
(Ishikawa, Suwabe, Nishide and Uneda)
Drilling with vibrations

4. The experimental system at the IWU
Torque & Force Sensor
Bending Element
Piezoelectric Actuator
CFRP Plate
Drilling with vibrations

5. The experimental system
Measured acceleration and amplitude of the vibrating system
Natural frequency calculated from the model by ANSYS – 513 Hz.
The estimated natural frequency based on measuring the spring constant of the system K N/mm and mass of 10 Kg yield natural frequency of 370 Hz. This was also evaluated experimentally.
Drilling with vibrations

6. Drilling CFRP with vibrations 8.2011
Example of test results with the following process parameters: rpm-3000, feed rate 0.06 mm/rev
Result of two experiments in each 60 holes were drilled with the same drill.
Drilling with vibrations

7. Drilling CFRP with vibrations 4.2012
We had problems with the measurement system.
In many experiments the recorded data was with saturation or not reasonable.
Drilling with vibrations

8. Drilling CFRP+Al stack 8.2011
Typical recorded data during drilling CFRP & Al stack
Drilling with vibrations

9. Drilling CFRP+Al 8.2011 Chip formation
Drilling with vibrations
Drilling without vibrations
Drilling with vibrations

10. Drilling CFRP+Al stack 4.2012
Drilling with vibrations

11. Drilling CFRP+Al stack 4.2012
Drilling with vibrations

12. Drilling with vibrations
Conclusions
Remarks:
1. The system was not recalibrated before starting the April 2012 experiments
2. The forth and torque measurement system ha to be fixed in a rigid way to the machine.
Develop better understanding of the relation between the material properties, the process parameters and the vibrations.
Changing the vibration parameters during the drilling process, this can shorten the time needed for finding the optimal vibration parameters under certain drilling parameters. Parameters like process parameters, tool type, type of material.
Drilling with vibrations

13. Drilling with vibrations
References
Drilling with vibrations