Title: Influence of cutting speed and tool wear on vibrations and process stability when turning Inconel 718 with PCBN tools

Authors: Оleksandr Gutnichenko; Volodymyr Bushlya; Jinming Zhou; Jan-Eric Ståhl

Addresses: Division of Production and Materials Engineering, Department of Mechanical Engineering, Lund University, Box 118, SE-22100, Lund, Sweden ' Division of Production and Materials Engineering, Department of Mechanical Engineering, Lund University, Box 118, SE-22100, Lund, Sweden ' Division of Production and Materials Engineering, Department of Mechanical Engineering, Lund University, Box 118, SE-22100, Lund, Sweden ' Division of Production and Materials Engineering, Department of Mechanical Engineering, Lund University, Box 118, SE-22100, Lund, Sweden

Abstract: Results of the study of cutting speed and tool wear influence on the vibrations and their nature during machining superalloy Inconel 718 with low cBN content (cBN-L) and binderless pcBN (bcBN) tools are presented. Cutting speed was varied from 2 to 14 m/sec while other cutting conditions were constant. The process evolution was studied with the wavelet transform of tool acceleration spectra. Behaviour of the dynamic system was found to vary with the cutting speed and the specifics of tool wear. It is shown that machining with bcBN tools was accompanied by appearance of significant vibration when cutting speed exceeded 5 m/sec, but the machining with cBN-L was characterised by the suppression of vibrations over the entire speed range. This was related to the difference of tool microgeometry development during the course of wear. The wear of bcBN tools, in contrast to cBN-L, was characterised by merger of crater and flank wear and formation of negative clearance angle. Such difference results in an increase of cutting forces 2-4 times as compared to cBN-L tools. Estimation of dynamic stability by 0-1 test confirmed the process instability when turning with bcBN tools at cutting speeds higher than 8 m/sec which concurs with chatter appearance. [Received 18 April 2013; Revised 21 October 2013; Accepted 24 November 2013]

Keywords: vibration; dynamic stability; tool wear; Inconel 718 turning; PCBN tools; cutting speed; process stability; superalloys; polycrystalline cubic boron nitride; tool microgeometry; cutting forces.

DOI: 10.1504/IJMR.2014.062444

International Journal of Manufacturing Research, 2014 Vol.9 No.2, pp.173 - 193

Published online: 29 Jul 2014 *

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