Application of Ultrasonics as Assistance in Machining Operations (pp. 159-172)
Authors: (A. Celaya, L.N. López de Lacalle, F.J. Campa, A. Lamikiz, Department of Mechanical Engineering, University of the Basque Country, Faculty of Engineering of Bilbao, Bilbao, Spain)
Abstract: The objective of the vibration assisted machining techniques is to improve the
traditional cutting processes by the application of an external vibration to the cutting edge
to achieve improvement in the chip removal mechanism and in the manufactured part
quality. Currently, two techniques are most common for vibration-assisted machining due
to their feasibility and industrial expectations: the Modulation-Assisted Machining and
the Ultrasonic Assisted Machining.
Modulation-Assisted Machining superimposes a controlled low-frequency oscillation
to the cutting process, typically up to 1000Hz with amplitudes up to 500 micrometers.
The mechanics of the chip formation is changed in that way, and cutting is divided into
discrete events by means of control of the modulation parameters. Thus, it improves
efficiency and process capability in precision machining processes.
On the other hand, Ultrasonic Assisted Machining consists in adding high frequency
excitation, which can reach 40 KHz, and low vibration amplitude, ranging between 3 and
30 micrometers, to the tool or workpiece to improve the cutting process. Ultrasonic
assisted machining technology demonstrates a range of benefits in both i) high precision
machining applications and ii) machining of difficult-to-cut alloys and brittle materials.
Ultrasonic assistance is applied to several cutting processes, but most of the research on
this method is focused on turning and drilling processes.
In this chapter, we report the basis of these techniques and the advantages and
drawbacks of ultrasonic assisted turning. Thus, the effect of tool vibration on cutting
process and workpiece surface quality was studied in turning of mild steel. Several
parameters of ultrasonic assisted turning (UAT) were monitored, including surface
roughness, tool wear, chip formation and tool temperature. The results obtained show that
ultrasonic vibration can improve the surface quality decreasing surface roughness and
cutting tool temperature and also a tool life increase is achieved compared to
conventional turning (CT).