• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.105-109
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• 1997

The effects of surface conditions of the C-2 cemented carbide substrate on the adhesion of diamond film were investigated. The substrates were pretreated for different times with Murakami's reagent and then the acid solution of an H2SO4-H2O2. The adhesion strength was estimated by a peeling area around the Rockwell-A indentation. The cutting performance of the diamond-coated tools was evaluated by measuring flank wears in dry turning of Al-17% Si alloy. The morphology of deposited diamond crystallites was dominated by (111) and (220) surfaces with a cubooctahedral shape. The diamond film quality was hardly affected by the surface conditions of the substrate. The variation of tool life with longer substrate etching times resulted from a compromies between the increase of film adhesion at the interface and the decrease of toughness at the substrate surface. The coated tools were mainly deteriorated by chipping and flaking of the diamond film form a lock of adhesion strength, differently from the wear phenomena of PCD tools.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.3
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• pp.68-74
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• 2003

Any one of the high precision spindle systems and guide way systems, the high stiffness of structure, the error compensation during assembly, high accuracy control system is inevitable technology for development of high precision machine tools. Especially, among these, design of spindle system is one of the most important technologies leading high precision of machine tool and high quality of manufactured products. A high speed and high precision spindle system, which will be used for final machining of ferrule, is designed considering the effect of heat cutting torque, cutting fore, and work-piece materials. The detailed design and analysis process are presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.389-394
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• 1993

Die making process is classified into design,manufacturing,polishing,assembly, and performance test. Die polishing is not a machining process by cutting edge of tool, but it is finishing by relative cutting movement under the surface contact between grinding particles and workpiece, and this process comprised 30~40% of total manufacturing hours. However, die polishing process is still performed by the skilled workers. Now a days, it is very difficult to secure skilled workers due to the hardworking environment and this situation will be getting worse in the future which has great difficulty of dies and molds industries.This process has the common problem on the elimination of tedious manual polishing among the tool making industries. Therefore this study is aimed at the development of an automatic polishing attachment which could be attached onthe spindle of CNC machine tool and controlled by the NC program data created by CAD/CAM system. As a result, this study will contribute the realization of automatic fine polishing process and improvement of quality level of dies and molds.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.980-983
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• 2002

In micro-machining, diamond tool is commonly used because it brings much better micro-machinability due to its edge sharpness. However, it is a big question even how thinly the sharp edge of a diamond tool can cut a ship from the workpiece surface. This paper is to investigate the critical cutting depth, at which the dominant cutting mode changes from chip formation to burnishing or vice versa, for a given edge radius. The theoretically critical cutting depth is 0.25$\mu\textrm{m}$(0.8$\mu\textrm{m}$) in cutting using a square type(V-type) diamond tool that has edge radius of 1$\mu\textrm{m}$(1.5$\mu\textrm{m}$). Experimentally, the dominant cutting mode changes and cutting surface becomes better at critical cutting depth. To get high quality surface, depth of cut must be critical cutting depth because less plastically deformed substrate is left on the surface.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.69-80
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• 2000

Generally, die polishing is a lime consuming process, resulting in 30∼50％ of the whole die manufacturing time. However, die polishing has not been automated yet, since it needs a great deal of experience and skill. This paper describes a new development of automated system for die polishing and focuses on the successful achievements of the element techniques to realize from hand skill to automation, as followings: (1) The 5 axes polishing system by the aid of robot with 2 degrees of freedom, is developed for the application of curved surface die. (2) The CAM system realizes a 5 axes tool path control for polishing and measuring. (3) The conductive elastic tool is able to meet curved surfaces of die and gives a high efficient and quality polishing characteristics. (4) The surface roughness measurement device with noncontact laser is developed and has a high reliability without surface damage.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.699-704
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• 2015

Laser-assisted machining has shown its potential to significantly improve product quality and reduce manufacturing costs; additionally, laser-assisted turning (LAT) and laser-assisted milling (LAM) have been studied by numerous researchers. A research study on the determination of the distance between the laser heat source and the tool for laser-assisted machining, however, has not yet been attempted; we conducted such an analysis by using a finite-element method and heat-transfer equation. The results of this analysis can be used as a reference for the determination of the distance between the laser heat source and the tool for laser-assisted machining.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1359-1367
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• 2001

Improvement of machine tool accuracy is an essential part of quality control in manufacturing process. Among of all the errors of a particular machine tool, the thermal errors of the spindle have a notably significant effect on machining accuracy and have a direct influence upon both the surface finish and geometric shape of the finished workpiece. Therefore, this paper proposed new measurement method for thermal errors of the spindle in machine tools. The thermal errors are measured by a ball bar system instead of capacitance sensor system. The novel measurement method using ball bar system is more efficient, easier to use than conventional measurement system. And also the ball bar system is possible to measure both geometric errors and thermal errors at the same time.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.161-165
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• 2001

End milling is one of the most widely used machining operations. It is associated with productivity and production quality progress. In metal cutting with up and down milling, moment is important factor to diagnose the cutting characteristics because the amount of tool wear directly influences the moment. In this study, the effects of number of milling cutting edges on the cutting performance, especially on the moment, are investigated. The results acquired through the cutting test measuring moment show that up milling is superior to down milling.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.52-59
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• 2006

Micro electrical discharge machining (EDM) and micro electrochemical machining (ECM) were studied for the fabrication of micro structures. Micro EDM has been used to machine micro structures from metals. However, since the tool wear is inevitable during the machining, the tool wear is drawback for the precision machining. Micro ECM is also used for micro machining and produces better surface quality than that of micro EDM. Moreover, since tool electrodes are not worn out, micro ECM is suitable for the precision micro machining. However, the machining rate is lower than that of micro EDM. In this paper, therefore, the hybrid machining process which uses micro EDM as roughing and micro ECM as finishing is introduced. By using this hybrid machining, a hemisphere with $100\;{\mu}m$ radius was fabricated and the efficiency of the process was investigated experimentally.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.118-126
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• 2000

Die-casting burr to casting process is removed by post-process for assembly and quality control of product. Though robot has been widely used for deburring job before. CNC exclusive machine is currently developed for high power, high speed machining and quick tool change. Deburring tool path with complex 3D curve type is defined to make out deburring NC program. But there is no efficient method to define it currently used methods with teaching probe on machine. In this study the efficient method to make out deburring NC program is developed. 5-axis digitizing machine is used to receive data of deburring path. And the post process for NC program generation is developed in consideration of the machining conditions. The developed system is not dependent on the skill of operator and has the advantage to maintain the flexibility of job to modify NC program due to the wear of tool and aging of the die casting.