• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.11a
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• pp.255-259
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• 2004

3-D micro structures and micro tools are fabricated using MEDM (Micro Electric Discharge Machining). To make micro structures, micro electro discharge milling process is applied. During micro electro discharge milling, electrode (tool) wears both axial and radial direction. To compensate tool wear which influences significantly machining accuracy, overlap machining path is proposed. Machining characteristics of micro electro discharge milling is investigated in considering of depth of cut and capacitance of discharge circuit. Micro complex shaped tools are fabricated using REDM (reverse electro discharge machining). Sacrificial electrode is machined through electro discharge milling process and is used as electrode to make micro tools. Using this process several micro tools shape of 'ㄷ', 'ㅁ' and 'o' are fabricated. With these complex shaped tools, micro machining is successfully applied repeatedly.

• Design & Manufacturing
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• v.11 no.2
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• pp.46-50
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• 2017

EPS used in lost foam casting elastic modulus is extremely low. So it is necessary to derive machining conditions for effective cutting. Therefore this study were analyzed end-milling machining conditions to affecting the surface roughness of EPS foam. The machining conditions were set to depth, feed, and RPM at 3-level. And 18experimental conditions were derived using mixed orthogonal array. The most important condition for surface roughness is RPM. In addition, RPM machining condition range test that can realize surface roughness less than $10{\mu}m$ was performed. he range of RPM conditions is more than 15,000. However the range of RPM conditions is a condition that is difficult to use in actual field. In the future variance analysis and experiments are needed to derive the range of machining conditions available.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.123-129
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• 2022

Quartz (SiO2) has high abrasion and heat resistances and excellent chemical and mechanical properties; therefore, it is used in various industries, such as machinery, chemistry, optics, and medicine. Quartz is a high-hardness and brittle material and is classified as the topmost difficult-to-cut material, which is because of the cracking or chipping at the edge during processing. Corner wear, such as cracks and chippings that occur during cutting, is a major cause for the deterioration in the machining quality. Therefore, many researchers are investigating various techniques to process quartz effectively. However, owing to the mechanical properties of quartz, most studies have been conducted on grinding, micromachining, and microdrilling. Few studies have been conducted on quartz processing. The purpose of this study was to analyze the machining characteristics according to the machining factors during the slot machining of quartz using a cubic boron nitride (CBN) tool and to select the optimal machining conditions using the Taguchi method. The machining experiment was performed considering three process variables: the spindle speed, feed rate, and depth of cut. The cutting force and surface roughness were analyzed according to the processing conditions.

• Design & Manufacturing
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• v.17 no.2
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• pp.15-21
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• 2023

In this study, a diamond turning machine and a laser-assisted machining module were utilized for the complex combined cutting of aspheric shapes and fine patterns on the surface of high-hardness brittle material, silicon. The analysis of material's form accuracy and corrective machining was conducted based on key factors such as laser output, rotational speed, feed rate, and cutting depth to achieve form accuracy below 1 ㎛ and surface roughness below 0.1 ㎛. The cutting condition and corrective machining methods were investigated to achieve the desired form accuracy and surface roughness. The rotational speed of the spindle and the linear feed rate of the diamond turning machine were varied in five stages for the cutting condition test. Surface roughness and form accuracy were measured using both a contact surface profilometer and a non-contact surface profilometer. The experimental results revealed a tendency of improved surface roughness with increased rotational speed of the workpiece, and the best surface roughness and form accuracy were observed at a feed rate of 5 mm/min. Furthermore, based on the cutting condition experiments, corrective machining was performed. The experimental results demonstrated an improvement in form accuracy from 0.94 ㎛ to 0.31 ㎛ and a significant reduction in the average value of the surface roughness curve from 0.234 ㎛ to 0.061 ㎛. This research serves as a foundation for future studies focusing on the machinability in relation to laser output parameters.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.114-123
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• 1998

In the end milling process, the information of the surface errors plays an important role in adaptive control systems for precision machining. As the measuring accuracy of the surface errors directly matches the control's, it is an important factor for evaluating the performance of the system. In order to obtain the surface errors, the prediction using the cutting force, torque, motor power etc. is frequently practiced owing to the easiness in measurement. In the implementation of the prediction, the information on the cutting depths make it concrete and precise. Actually the axial depth of cut limits the range of the calculation. In general, it is not easy to know the cutting depths due to irregular shape of workpieces, inaccurate positioning of them on the table of machine tool, and machining error in the previous cutting. In addition to, even if cutting depths are informed, it is difficult to match the individual position of the cutter on the varying shape of the work material. This work suggests an algorithm estimating the cutting depths based on cutting force and makes it precise to predict the surface error. The proposed algorithm can be applied in more extensive cutting situations, such as presence of the tool wear, change of the work material hardness, etc.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.35-39
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• 2010

Generally, ceramic material is very difficult to machine due to high strength and hardness. However, ceramic material can be machined at high temperature by plastic flow as metallic material due to the deterioration of the grain boundary glassy phase. Recently, a new method was developed to execute cutting process with CBN cutting tool by local heating of surface with laser. There are various parameters in LAM because it is a complex process with laser treatment and machining. During laser assisted machining, high power results in reducing of cutting force and increasing tool life, but excessive power brings oxidation of the surface. The effect of laser power, feed rate, cutting depth and etc. were investigated on the life of cutting tool. Chips were observed to find out suitable machining conditions. Chips of SSN had more flow-types than HIPSN. It means SSN is easier to machining. The life of cutting tool was increased with increasing laser power and decreasing feed rate and cutting depth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2430-2435
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• 2015

In order to achieve high flexibility in manufacture, analysis of chip's shape is one of the most important problems. This paper describes the change of machining characteristics in workpiece materials depending on turning clearance angle. The experiments start from choosing three workpiece materials that are SM45C(machine structural carbon steel), STS303(stainless steel), SCM415 (chrome-molybdenum steel). Then, the experiments show specifically how features of selected materials changed when they were processed with diverse machining depths and with feed rate starting from fixed rotational speed. Especially, the experiments were also analyzed in chip's shape and wear of insert tip. In conclusion, these experiments show that chip's shape was changed by quality of the materials, depth of cut, and conveying speed. When machining feedrate and machining depth were 0.10mm/rev and 0.3mm respectively, workpiece materials showed the best shapes, not categorizing quality of the materials and machining characteristics.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.3
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• pp.104-114
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• 2022

The purpose of using coolant in machining is both to increase a tool life and also to prevent product deformation and thus, stabilize the surface quality by lubricating and cooling the tool and the machining surface. However, a very small amount of cutting mist should be used because chlorine-based extreme pressure additives are used to generate environmental pollutants in the production process and cause occupational diseases of workers. In this study, medical titanium alloy (Ti-6Al-7Nb) was subjected to a processing experiment by selecting factors and levels affecting cutting power in the processing of the Aerosol Dry Lubrication (ADL) method using vegetable oil. The machining shape was a slot to sufficiently reflect the effect of the cutting depth. As for the measurement of cutting force, the trend of cutting characteristics was identified through complete factor analysis. The factors affecting the cutting force of ADL slot processing were identified using the reaction surface analysis method, and the characteristics of the cutting force according to the change in factor level were analyzed. As the cutting speed increased, the cutting force decreased and then increased again. The cutting force continued to increase as the feed speed increased. The increase in the cutting depth increased the cutting force more significantly than the increase in the cutting speed and the feed speed. Through the reaction surface analysis method, the regression equation for predicting cutting force was identified, and the optimal processing conditions were proposed. The cutting force was predicted from the secondary regression equation and compared with the experimental value.

• Journal of the Korean Ceramic Society
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• v.30 no.5
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• pp.420-426
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• 1993

The machinability of ceramics has been experimentally studied. The experiments were conducted on alumina cernmics of various purity, quartz, and cordierite using the sintered diamond tools and CBN tools. Tool wasre, surface roughness, and cutting resistence were measured and analysed. It was found that the workpieces could be machined with the diamond and CBN tools, but the sintered diamond tools were more efficient for the machining of the high strength ceramics. The machining of alumina ceramics with sintered diamond tools showed that (1) wet machining prolonged tool life comparing with dry machining, (2) workpiecewith higher purity had better surface roughness, (3) severe cutting conditions led to the chipping and fracture of tool and increase of the surface roughness and cutting resistance, (4) 20~40m/min of cutting speed, 0.01~0.02mm/rev of feed, and 0.1~0.2mm of cutting depth are suggested as proper cutting conditions for the high strength ceramics.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1338-1343
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• 2007

High-efficient machining, which means cutting a part in the least amount of time, is the most effective tool to improve productivity. In this study, a new feed optimization method based on the cutting power regulation was proposed to realize the high-efficient machining in turning process. The cutting area was evaluated by using the Boolean intersection operation between the cutting tool and workpiece. And the cutting force and power were predicted from the cutting parameters such as feed, depth of cut, spindle speed, specific cutting force, and so on. Especially, the reliability of the proposed optimization method was validated by comparing the predicted and measured cutting forces. The simulation results showed that the proposed optimization method could effectively enhance the productivity in turning process.