Self-excited vibration, known as chatter, limits material removal rate, surface finish and accuracy in machining, and may even cause structural damage to components of the machining system. Machining stability may be enhanced by a variety of methods, from moving machining parameters to stable regions, or using actively actuated tools specially designed to obstruct self-excitation, or even by passively enhancing the stiffness or damping of the system as to soften the critical mode of vibration. Although there are many approaches to reduce chatter, not all of them are always effective in every situation. Moving machining parameters is restricted by workpiece machinability. Active damping mechanisms require large contraptions to function and have limited effectiveness when dealing with high frequency chatter. Passive damping approaches have essentially entailed tuned mass dampers which require delicate finetuning and drastic alterations to the tool structure in order mount the vibration absorber system. This research presents an elegant and innovative application involving electrical discharge texturing for chatter suppression that takes advantage of frictional forces to passively damp self-excited vibrations. This technique proved effective in a frequency range from 100 to 4000 Hz achieving damping enhancements of more than 400% without the need of any tuning and showing repeatable damping values after subsequent assembly and disassembly cycles. When applied to a grooving operation the technique proved effective in increasing the limiting width of cut by more than 120%. / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26978 |
| Date | January 2021 |
| Creators | Pereira Coelho, Felipe |
| Contributors | Koshy, Philip, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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