Papers by Keyword: Ductile Mode Machining

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Authors: A.K.M. Nurul Amin, A.A. Che Omar, M.A. Mohammed Kamal, Mahmoud M.A. Nassar, N.F. Mohd Zaib, Muammer Din Arif
Abstract: Soda lime glass is widely used in optics, chemical apparatus, camera lens, micro gas turbines, light bulbs etc. on account of its high hardness, corrosion resistance, and excellent optical properties. These require high dimensional accuracy and flawless surface finish. However, soda lime glass is inherently brittle leading to subsurface crack propagation and fracture which compromise its functionality. To avoid these defects, the machining needs to be performed under ductile mode conditions. Therefore, this research investigates the viability and requisite conditions for achieving ductile regime machining (DRM) in high speed micro-end milling of soda lime glass. Machining was performed at high cutting speeds (30,000 to 50,000 rpm), feed rate (5 to 15 mm/min), and depth of cut (3 to 7 μm). A surface profilometer was then used to measure the surface roughness and a scanning electron microscope (SEM) used to scrutinize the resultant machined surfaces. The results demonstrate that ductile streaks and rounded gummy chips (without sharp or jagged edges) are produced in all runs. In addition, there are no subsurface cracks and the minimum surface roughness attained is 0.08μm. These indicate that DRM of soda lime glass is obtainable using high-speed micro end milling in a conventional end mill with tungsten carbide inserts.
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Authors: Muhammad Arif, Mustafizur Rahman, Yoke San Wong
Abstract: Glass is an important engineering material. It is widely used in semiconductor, optical, micro-electronics and many other fields. However, glass is not amenable to machining with conventional approach because of its low fracture toughness. To achieve high quality surface finish on optical components, glass must be machined in ductile mode. Compared to single point cutting processes, end-milling can achieve improved material removal rate in machining fracture free surface on brittle material. This paper presents the results of an experimental investigation into microcutting of glass by end-milling. Side-cutting tests have been performed on soda-lime glass workpiece at multiple feeds and radial depth of cuts to obtain fracture free machined surface. The tests were designed to investigate the effect of feed per edge and radial depth of cut on the cutting mechanism at low cutting speed. Experimental results indicate that feed per edge is the most dominant factor that dictates the occurrence of brittle-ductile transition point in the milling process of glass. It has been proved experimentally that fracture free surface can be machined on glass at high radial depth of cut if the feed per edge is sufficiently small.
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Authors: Hiroaki Tanaka, Shoich Shimada, Naoya Ikawa
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Authors: A.K.M. Nurul Amin, A.A. Che Omar, M.A.Mohammed Kamal, Mahmoud M.A. Nassar, N.F. Mohd Zaib, Muammer Din Arif
Abstract: Soda lime glass is used extensively in camera lens, micro gas turbines, light bulbs, tablewares, optics, and chemical apparatus owing to its high hardness, excellent optical properties, and good corrosion and chemical resistance. Such applications of soda lime glass demand high machining and finishing precision. On the other hand, machining of glass poses significant challenges due to its inherent brittleness. The process of removal of material from glass, if not done in ductile mode, can generate subsurface cracks and brittle fractures which have adverse effects on its functionality. This research investigates the high speed micro-end milling of soda lime glass in order to obtain ductile regime machining. It has been found by other researchers that ductile mode machining can avoid sub-surface cracks and brittle fractures. However, in ductile mode machining, the gummy chips settle permanently on the machined surface affecting adversely the surface finish. In order to avoid such chip settlement, compressed air was directed using a special air delivery nozzle to blow away the resultant gummy chips, thereby preventing them from settling on the machined surface. Response surface methodology (RSM) and a commercial NC end mill were used to design and perform the machining runs, respectively. Machining was done using: high spindle speeds from 30,000 to 50,000 rpm, feed rates from 5 to 15 mm/min, and depth of cuts from 3 to 7 μm. Three different diameter carbide tools were used: 0.5, 1, and 2 mm. A surface profilometer was used to analyze the surface roughness of the resultant machined surface. Subsequently, the data was used for finding the best combination of cutting parameters required to obtain the lowest surface roughness. The results demonstrate that high speed machining is a viable option for obtaining ductile regime machining and generating machined surfaces with very low surface roughness in the range of 0.08μm – 0.22 μm, using 0.5 mm carbide end mill cutter.
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Authors: Xin Hong Yang, Yu Min Zhang, Jie Cai Han
Abstract: An experimental investigation is carried out to machine SiC ceramic material through method of high speed plane lapping with fixed abrasive. The results show that the material removal mechanism and the surface roughness are chiefly related to the granularity of abrasive and the lapping pressure for the brittle materials such as SiC ceramic. It is easily realized to machine SiC ceramic material in ductile mode with a high efficiency and a low cost using W3.5 grit under a lapping pressure of 0.1MPa and then a smooth surface with surface roughness of Ra 2.4nm can be achieved.
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Authors: Nobumasa Yokemura, Kenichiro Imai, Hiroshi Hashimoto
Abstract: In this study, basic experiments involving machining using a rotational tool were conducted with the aim of increasing the volume of material removed rate in ductile-mode machining of Si wafers. The machining surface and machining force was compared to experimentally clarify the material removal process for a single cutting edge, the critical cutting thickness tc at which occurs of cracks was set as the machining condition. Then, the three machining modes were experimentally revealed. As the result, the ductile-mode machining surface was obtained that the total depth of cut was under less than 78.5μm on ductile-brittle-mode machining.
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