ScienceDirect Available online at www.sciencedirect.com Procedia Manufacturing 48 (2020) 283–293 2351-9789 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the Scientifc Committee of the NAMRI/SME. 10.1016/j.promfg.2020.05.049 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the Scientifc Committee of the NAMRI/SME. 1. Introduction Milling is one of the most extensively used machining operations in metal cutting industries because of its capability to cut different ranges of materials. High-speed milling is chosen for attaining higher productivity and better surface quality [1]. Undesired vibrations during high-speed milling are the main restrictive factors that limit the productivity and affect the life of the tool and certain components of the machine tool. Among different types of vibrations such as impulsive, forced and self-excited regenerative vibration, self-excited regenerative vibration, also considered as chatter negatively influences the dimensional accuracy and surface quality of the machined part. Various detrimental effects of chatter are given in Fig. 1. Attempts were made to study the mechanism, behavior, and factors responsible for chatter during machining. Tobias and Tlusty [2,3] explained the mechanism of chatter in orthogonal and oblique cutting by self-excited regenerative vibration and also proposed the stability lobe for selecting chatter-free machining parameters i.e. depth of cut and spindle speed. Avoidance of chatter is possible by either changing the system behavior such as stiffness enhancement, active or passive damping, etc. [4-8] or by selecting stable cutting parameters with the application of stability lobe diagrams. Out Keywords: High-speed milling; Chatter; Stability lobe diagrams; Operational Modal Analysis (OMA) Prediction of Stability Lobe Diagrams in High-Speed Milling by Operational Modal Analysis Vineet Paliwal, N. Ramesh Babu* Manufacturing Engineering Section Department of Mechanical Engineering IIT Madras, Chennai 600036, India. * Corresponding author. Tel.: +91 44 2257 4675; fax: +91-044-2257-4652. E-mail address: nrbabu@iitm.ac.in Abstract Self-excited regenerative vibration or chatter limits the primary requirements like productivity, surface finish and dimensional accuracy of high- speed machining. It is the most critical factor that severely affects the tool-life and life of the machine tool. Out of several methods followed for suppressing and avoiding chatter, machining conditions chosen with stability lobe diagram is the most reliable way. Stability lobe diagrams are typically generated by knowing specific cutting force coefficients and tool point frequency response functions (FRFs). Inaccurate use of tool point FRFs significantly affects the stable regions of stability lobe diagrams. As tool-point FRFs are influenced by gyroscopic effect, centrifugal force, thermal change in bearing dynamics, etc. during machining, it is important to consider the effect of these factors on tool point FRFs in order to generate accurate stability lobe diagrams. The present work covers a new approach for estimating tool point FRFs during machining operations, employing cutting tool vibration signals. For measuring the vibration at the tip of end mill at different spindle speeds, a non-contact laser vibrometer is used. In order to remove the tooth pass frequency and its harmonics from the measured signals, a comb filter is employed. The filtered signal is subjected to Operational Modal Analysis (OMA) in order to derive tool point FRFs. With the estimated FRFs at different spindle speeds, the stability lobe diagrams are drawn for high-speed milling machine. Comparative study of stability lobe diagrams, drawn with static modal analysis and Operational Modal Analysis, have shown that the cutting conditions chosen from stability lobe diagram derived with OMA, are found to be more realistic for avoiding chatter during high-speed milling applications. 48th SME North American Manufacturing Research Conference, NAMRC 48 (Cancelled due to COVID-19)