• Journal of the Korean Society for Heat Treatment
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• v.6 no.1
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• pp.1-8
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• 1993

In this paper, the surface roughness influenced by Sm45C hardness in high frequency induction hardening and mechanical characteristics for the changed Hv 598 part and the unchanged hardness Hv 223 part by use of cermet and ceramic cutting tools was experimentally examined. Finally, we could be had some important results by processing surface roughness on cutting conditions such as cutting speed, feed rate, depth of cut and changes of tool nose radius. The results are summarized as follows. 1. In case of the same cutting condition, the hardness of workpiece was high and acquired the best processing surface roughness when the radius of the tool nose had 0.8 mm and feed rate was 0.04 mm/rev. 2. In case of the hardness of workpiece, though the cutting speed didn't have an effect on processing surface roughness, the less feed rate and the more processing surface roughness improved. On the other hand, the low inside the hardness of workpiece, the more cutting speed and the more feed rate increase, the processing surface of roughness improved. 3. Regardless of the hardness of workpiece, the change of the cutting depth didn't have great effect on the surface roughness. 4. On cutting the high surface hardness part with cutting tools of cermet and ceramic, it can be acquired the higher processing surface roughness because it hadn't been taken effect on cutting speed, In case of the cutting process of the low inside hardness part the two cutting tools have acquired the similar processing surface roughness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.961-964
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• 1997

In this paper, grinding characteristics of ultra high speed cylindrical plunge grinding was investigated by use of vitrified CBN wheel. From the experimental result, it was convinced that grinding power is decreased according to the increase of wheel and workpiece speed due to changing of grinding mechanism which decreases depth of cut and length of contact curve according to increment of wheel speed. And also, stock removal reduction of each gram lead to improvement of surface roughness by increasing the wheel speed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.63-70
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• 1999

Surface hardening of plain carbon steel (SM45C) by Laser are usually much finer and stronger than those of the base metals. The present study was under taken to investigate the wear resistance and a processing parameters such as, power density, pulse width, defocusing distance, and molten depth for surface modification of plain carbon steel. The wear test was carried out under experimental condition using the wear test device, and in which the annular surfaces of wear test specimens as well as mating specimen of alumina ceramics($Al_2O_3$) was rubbed in dry sliding condition. It is shown that molten depth and width depend on defocusing distance. The wear loss on variation of sliding speed was much in lower speed range below 0.2m/sec and in higher speed range above 0.7m/sec, but wear loss was little in intermediate speed range. It depends on oxidation speed and wear speed.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.233-243
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• 1998

The demand of high speed machining is increasing due to the high speed cutting and grinding provides high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting or grinding. This paper describes a design process of an active magnetic bearing system for a high speed grinding spindle with power 5.5kW and maximum speed 60,000rpm. Magnetic actuators are designed by the magnetic circuit theory considering static load condition, and examined with FEM analysis. Dynamic characteristics are also considered, such as bandwidth, stiffness, natural frequency and static deflection. System characteristics are simulated with a rigid rotor model.

• 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.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.24-31
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• 2003

In the gas cutting of plate steel, the quality of the cut surfaces and sections is strongly dependent on the cutting conditions such as cutting speed, kerf width, plate thickness, material, distance between tip and specimen, and cutting oxygen pressure etc. The cutting tests of plate steel were carried out using CNC gas cutting machine. This paper deals with cut surface and section characteristics of plate steel in CNC gas cutting. Both top and bottom widths of kerf, the surface roughness(Ra, Rmax) of cutting surfaces are measured under various cutting conditions such as cutting speed, material, distance between tip and specimen, and cutting thickness. The photographs of cut surface and cut section are also analyzed under various cutting conditions.

• Journal of the Korean Graphic Arts Communication Society
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• v.22 no.2
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• pp.101-110
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• 2004

The local surface strength variation of coated papers were measured at various speeds on a number of coated paper samples to study the effects of speed and ink tack on coating pick. Coating pick phenomenon is observed in an ink transfer variation curve as a decrease in the slope of the curve. On the other hand, it causes an actual decrease in net ink transfer to paper with an increase in speed. The effect of speed on coating pick depends on ink tack, ink film thickness and surface properties of coating layer formation of paper. A novel device to measure the surface strength can rate the coating paper in a different order. Comparison are made between dry test of coating paper pick and wet coating pick test of printing in IGT printability tester. Coating formulation is the main key to prevent from coating pick. The binder level increases, the coating pick and the slop decrease. The piling on blanket in printing is a problem when the coating pick is occur on a local area rather than average surface strength of coated papers.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.124-130
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• 2008

The effect of nitrogen gas pressure in arc ion plating on surface properties of the TiN-coated high speed steel(SKH51) is presented in this paper. The surface roughness, micro-particle, micro-hardness, coated thickness, atomic distribution of TiN, and adhesion strength are measured fur various nitrogen gas pressures. It has been shown that the nitrogen gas pressure has a considerable effect on the surface roughness, adhesion strength, atomic distribution of TiN, and surface deposition of TiN of the high speed steels but that it has little influence on the micro-hardness and coated thickness.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.292-296
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• 2002

In the present investigation, the improvement of processing efficiency in the high speed machining of GC250 is explored. This study is to evaluate the tool performance in difficult-to-material using the new developed tool. Tool performance evaluation are conducted by tool wear, surface roughness, chattering in machined surface. The tool wear of A type was smaller than B type. In type B tool the chatter mark was observed in machined surface. The good surface roughness was obtained in type A tool. Consequently, the tool performance of A type is better than B type.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.192-197
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• 2002

In this study, examined the cutting characteristics of alumuminum alloy AC8A-T6 that is used to present car piston materials. And in been holding materials machining empirically escape as result that experiment comparison changing the cutting speed and feed on various condition to choose efficient machining condition. The following results can be summarized from this research. 1. As the cutting speed decreased, principal cutting force and thrust cutting force is increased, and reason that cutting force interacts greatly in the low cutting speed is thought by result by BUE's stabilization. 2. The feed speed and cutting speed increase, friction factor is decrescent and the cause appeared the thrust cutting force is fallen than cutting force relatively because chip flow according to increase of the feed rate is constraint. 3. Though specific cutting resistance grows cutting area and the feed rate are few, the cause was expose that shear angle decreases by rake face of tool gets into negative angle remarkably as wear of a cutting tool or defect part of workpiece is cut. 4. Cutting speed do greatly depth of cut is slow, surface roughness examined closely through an experiment that becomes bad, and know that it can get good surface that process cutting speed because do feed rate by 0.1mm/rev low more than 250m/min to get good surface roughness can.