Cryogenic Machining of Ti-6Al-4V
Licentiate thesis, 2018
Turning experiments on Ti-6Al-4V revealed that using the same setup (same tool holder and nozzle configuration, comparable coolant pressure) gives very similar results in terms of surface integrity when using cryogenic cooling with liquid nitrogen compared to flood-cooling with emulsion. The choice of coolant did not have a significant impact on surface roughness, microstructure in the near-surface layer or residual stresses. The residual stresses were compressive in all cases, but increased tool wear shifted the residual stress depth profiles towards more compressive stresses. Due to the relatively small nozzle size used, however, the flow of cryogenic coolant was insufficient to match the tool life obtained with emulsion cooling.
In face milling of Ti-6Al-4V with liquid carbon dioxide and emulsion, it was shown that notch wear and chipping were the main wear mechanisms determining the tool life, rather than abrasive wear, i.e. flank wear. Comb cracks were formed in both cooling conditions. However, cryogenic cooling with liquid carbon dioxide greatly delayed the lateral propagation of the comb cracks, thereby delaying the chipping of the cutting edge. Tool life was shown to improve with higher flow rates of coolant, the effect being stronger when using liquid carbon dioxide compared to flood-cooling with emulsion. Moreover, the difference in terms of tool life between cryogenic cooling and flood-cooling with emulsion decreased at higher cutting data.
Chalmers, Industrial and Materials Science, Materials and manufacture
S. Isakson, M.I. Sadik, A. Malakizadi, P. Krajnik. Effect of cryogenic cooling and tool wear on surface integrity of turned Ti-6Al-4V
Influence of Coolant Flow Rate on Tool Life and Wear Development in Cryogenic and Wet Milling of Ti-6Al-4V
Procedia CIRP,; Vol. 46(2016)p. 91-94
Paper in proceeding
The role of PVD coating and coolant nature in wear development and tool performance in cryogenic and wet milling of Ti-6Al-4V
Wear,; Vol. 386-387(2017)p. 204-210
Areas of Advance
Manufacturing, Surface and Joining Technology
Metallurgy and Metallic Materials
Delta, Hörsalsvägen 7A
Opponent: Assoc. Prof. Franci Pusavec, University of Ljubljana, Slovenia.