Influence of magnetic field from permanent magnets on chatter suppression in end milling of titanium alloy (Ti6A14V) /
Machining of metals is generally accompanied by a violent relative vibration between work and tool, known as chatter. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. Chatter has detrim...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur:
Kulliyah of Engineering, International Islamic University Malaysia ,
2013
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | Machining of metals is generally accompanied by a violent relative vibration between work and tool, known as chatter. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. Chatter has detrimental effects on the topology and dimensional accuracy of the work-piece; tool life, and productivity. The researcher has developed a novel method for chatter control in end milling to address this issue. The method consists of two ferrite permanent magnet bars (dimensions: 1″ x 6″ x 3″), mounted close to the cutting tool using a specially designed fixture, to provide a uniform magnetic field of 2500-2700 Gausses (approximately). A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts. The experiments were designed using the Design Expert software following the Central Composite Design (CCD) concept of Response Surface Methodology (RSM). Independent variables cutting parameters in the design were cutting speed, feed, and depth of cut. Machining tests were conducted for two different conditions – with and without the application of magnets. Mitutoyo SURFTEST SV-500 and Scanning Electron Microscope (SEM) were used to measure the resultant surface roughness and chip segmentations, respectively. For vibration monitoring and analysis, an online vibration monitoring system comprising a16 channel rack, DAQ card and Datalog DASY Lab 5.6, with built-in Fast Fourier Transform (FFT), were used. It was observed that cutting under the presence of magnets lead to a maximum reduction of 60% and an average reductions in vibration ampiltudes by approximately 30%. This resulted due to the damping effects of the magnets on the vibratory motion of the tool. The SEM analysis of chip serrations demonstrated that the chip formations were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter. Surface roughness was found to be reduced by an average of approximately 40% due to relatively stable cutting. Minimum surface rougness value achieved was 0.22 μm, which indicated that it would be possible to eliminate the need for subsequent finishing operations of grinding and polishing if the new technique of chatter suppression is applied in end milling of Ti6Al4V. |
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| Item Description: | Abstract in English and Arabic. "A dissertation submitted in fulfilment of the requirement for the degree of Master of Science (Manufacturing Engineering)."--On t.p. |
| Physical Description: | xviii, 150 leaves : ill. ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 127-131). |