Processing and damping properties of sputtered NiTi thin films for tools in machining processes

Kahleyß, F.1, a; Surmann, T.1, b; Machai, C.1, c; Biermann, D.1, d; Lima de Miranda, R.2, e; Zamponi, C.2; Quandt, E.2

1)
Institut für Spanende Fertigung, Technische Universität Dortmund, Baroper Str. 301, 44227 Dortmund
2)
Institute for Materials Science, University of Kiel, 24143 Kiel

a) kahleyss@isf.de; b) surmann@isf.de; c) machai@isf.de; d) biermann@isf.de; e) rlm@tf.uni-kiel.de

Kurzfassung

Many machining processes today suffer from vibrations which reduce the possible machining parameters of modern machine tools considerably or otherwise, cause an increase of tool wear and a poor surface quality. Especially, the long and slender tools, which are used in internal longitudinal turning or in milling operations of cavities, are susceptible to vibrations due to their small axial section modulus. Earlier researches have shown that shape memory alloys have a high potential to dampen vibrations, especially at low oscillation frequencies. Further investigations showed that the NiTi-alloys also have a certain damping capability when they are exposed to high frequency vibrations over hundred cycles per second. Consequently, the SMA elements can reduce process vibrations when they are implemented into the tool bushing. This way, they enhance the usable parameter range of modern production processes. Nevertheless, it is necessary to apply NiTi elements as close as possible to the tool tip in order to achieve the maximum damping effects, since damping is dependent on a structure’s velocity. The application of NiTi thin films on tool shafts is an innovative approach to improve their damping properties. The paper concentrates on the aspects of the application of the thin films as well as on the determination of their material properties. Furthermore, the work reported in this paper describes the influence of the coating on the modal parameters of such tool shafts. Simulation software is used to transfer the results of the modal analysis to a modeled machining process. The resulting stability charts show the relevance of the NiTi thin films concerning stable machining processes related to the cutting depth and the revolution speed of the spindle.

Schlüsselwörter

NiTi, shape memory alloys, thin film, damping, machining, simulation

Veröffentlichung

In: SMST Extended Abstracts 2010, SMST 2010 – International Conference on Shape Memory and Superelastic Technologies, 16.5.-20.5. 2010, Asilomar Conference Center, Pacific Grove, USA, D. S. Grummon; X. Fei; M. R. Mitchell; M. Mertmann (Hrsg.), S. 64-65