Master Thesis Defense: Alptunç Çomak
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DYNAMICS AND CHATTER STABILITY OF MULTI DELAY MACHINING SYSTEMS

Alptunç Çomak
Industrial Engineering, M.Sc. Thesis, 2013 

Thesis Jury
Prof. Dr. Erhan Budak (Thesis Supervisor), Assoc. Prof. Bahattin Koç, Assoc. Prof. Bülent Çatay, Assoc. Prof. Ali Koşar, Assoc. Prof. Ayhan Bozkurt

Date &Time: July,17th, 2013 - 10.00

Place: FENS G032

Keywords: Chatter Stability, Special Milling Tool, Parallel Milling, Parallel Turning

Abstract

Machining is an industrial process in which parts are shaped by removal of unwanted material in the forms of chips. Manufacturing industry today demands shorter production times and high quality parts at competitive cost.  Increased MRR (material removal rate) in milling and turning may provide high productivity but elevated forces and vibrations are still major obstacles to fulfill these requirements. Chatter vibrations may limit the full potential of machining productivity. In this thesis, chatter stability of multi delay systems is investigated. As examples of multi delay systems, variable tooth spacing tools such as variable pitch and helix milling cutters and parallel milling operations are investigated. Although there are few studies about the chatter stability of variable tooth spacing tools, no work has been reported on optimum design for a given cutting condition. Optimization studies are carried out to determine the optimum variable tool geometry and a new design methodology is presented. Moreover, for parallel milling operations, an analytical solution methodology which is based on frequency domain analysis is proposed to solve the chatter stability for the first time in the literature. Optimum cutting conditions are identified and effects of process parameters and workpiece dynamics on the chatter stability of parallel milling are shown. Since the operation contains single time delay, optimization studies are carried out to determine the optimum cutter dynamic properties in parallel turning. Simulated conditions are verified by time domain and experimental tests.