Experimental investigations on longitudinal-torsional vibration-assisted milling of Ti-6Al-4V

Abstract

In vibration-assisted milling (VAM), an additional high-frequency oscillation is superimposed on the kinematics of a conventional machining process. This generates oscillations of the cutting edge in the range of a few micrometers, thereby causing a high-frequency change in the cutting speed and/or the feed. Consequently, a reduction of cutting forces, an increase of the tool life, and an improvement of the workpiece quality can be achieved. This paper shows and compares the effects of longitudinal and longitudinal-torsional (L-T) vibrations on the cutting force, the tool life, and the surface quality when milling Ti-6Al-4V. In comparison with the conventional milling process, the cutting forces are significantly reduced and the surface finish of the workpiece can be improved by introducing ultrasonic vibrations to the milling process. Longitudinal-torsional vibration assistance showed better overall process performance than the pure longitudinal vibration assistance.

Surface finishing of hard-to-machine cladding alloys for highly stressed components

“…A good correspondence with the findings of other authors, who investigated ultrasonic-assisted machining of hard-tomachine high strength materials, was observed [21][22][23][24]. Thus, the results from recent investigations showed also primarily a reduction of the cutting forces [23] and lower residual stresses resulting from the ultrasonic-assisted milling [24]. In this study for the first time a direct quantitative comparison between the cutting forces and the surface residual stresses could be achieved by application of USAM with ball end milling tools.…”

“…The finishing milling was performed after the weld metal was post weld heat treated as recommended and shows high mechanical strength. A good correspondence with the findings of other authors, who investigated ultrasonic-assisted machining of hard-tomachine high strength materials, was observed [21][22][23][24]. Thus, the results from recent investigations showed also primarily a reduction of the cutting forces [23] and lower residual stresses resulting from the ultrasonic-assisted milling [24].…”

“…It could be shown that the force reduction is the result of a superimposed movement in the range of the oscillation amplitude (up to 14 μm) of the cutting edge, which is mainly in the cutting direction and therefore reduce the net cutting time and the toolworkpiece contact rate. Similar results could be shown by Rinck et al likewise at Ti-6Al-4V [24]. It has also been observed that USAM provides beneficial results in the milling of fibre reinforced plastics [25].…”

“…Further investigation will also focus other materials, which are hard-to-machine, like mentioned, CoCr alloys and austenitic FeNi alloy to prove a cross-material benefit of the ultrasonic-assisted milling for additively manufactured or repair welded components. On the basis of the results of other authors which found beneficial effects for ultrasonicassisted milling for several hard-to-machine Ti, Ni and steel alloys, e. g. [19,24,26], it can be strongly assumed that these processes are also suitable for other materials. Another promising application may be the machining of, for example, new and innovative material classes such as intermetallic FeAl (iron aluminide alloys) [35].…”

Review of new developments in machining of aerospace materials

“…Comprehensive experimental investigation of the effects of longitudinal (LVAM) and longitudinal-torsional (LTVAM) vibrations on the cutting force, the tool life, and the surface quality when milling Ti-6Al-4V was presented in [50]. LTVAM showed better overall process performance than the pure longitudinal vibration.…”