• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.275-280
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• 2001

Recently, the trends of industrial products grow more miniaturization, variety and mass production. Micro drilling which take high precision in cutting work is requested more micro hole and high speed working. Especially, Micro deep hole drilling is becoming more important in a wide spectrum of precision production industries, ranging from the production of automotive fuel injection nozzle, watch and camera parts, medical needles, and thick multi-layered Printed Circuit Boards(PCB) that are demanded for very high density electric circuitry. This paper shows the tool monitoring results of micro drill with tool dynamometer. And additionally, microscope with built-in monitor inspection show the relationship between burr in workpiece and chip form of micro drill machining.

• Laser Solutions
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• v.18 no.2
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• pp.11-13
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• 2015

Pressure-drop in a micro-channel is critical when a hole diameter is less then 100um with the high aspect ratio, more than 40. To minimize these pressure loss for micro-channel applications is important and there would be the best hole diameter, taper angle, and their combinations. In this work, the parametric study for laser drilling of anodized material is conducted to obtain the micro-channel hole with high aspect ratio.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.953-956
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• 1997

Micro drilling characteristics by EDM method was investigated. In detail, Micro tool electrode for EDM drilling was machined by use of WEDG method and micro hole was drilled using the machined tool electrode in SUS plate. The machining accuracy and time was compared in a different dielectric fluid. As a result, it was convinced that this method could be utilized as a fabrication technology of micro mold or micro 3 dimensional parts.

• IE interfaces
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• v.12 no.2
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• pp.337-345
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• 1999

This paper presents the optimization of a drilling operation subject to machining constraints such as power, torque, thrust, speed and feed rate. The optimization is meant to minimize the machining time required to produce a hole. For the first time, the effects of a pilot hole are included in the formulation of the machining constraints. The optimization problem is solved by using the geometric programming technique. The dual problem is simplified based on the characteristics of the problem, and the effects of machining constraints on the machining variables are identified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.187-188
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• 2009

• Journal of Welding and Joining
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• v.8 no.4
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• pp.76-82
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• 1990

Lots of research works have been done to improve the accuracy of the hole drilling method to measure residual stress by many investigators. In this study, first, size effect of specimen was analyzed based on the solution of hole in a strip under tension. If the ratio of hole diameter tothe strip width is less than 0.2, the stress distribution around hold may be given from the solution of hole in an infinite plate. Second, the residual stress above $0.6{\sigma}_y$(yield stress) may be measured less than the actual stress by 10-15 percent. Third, eccentricity of hole relative to the rosette center effects on the accuracy of residual stress measurements by 10 percent. The error due to eccentricity of hole can be corrected by the iteration method or the direct method.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.148-154
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• 2001

Drilling is one of the most important operations in machining industry and usually the most efficient and economical method of cutting a hole in metal. From automobile parts to aircraft components, almost every manufactured product requires that holes are to be drilled for the purpose of assembly, creation of fluid passages, and so on. It is therefore desirable to monitor drill wear and hole quality changes during the hole drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. A drill-wear monitoring system provides information about drill status. With the information, optimum planning for tool change is possible. And drill-wear monitoring system in needed to evaluated drilled hole quality and the wear of drill. Accordingly, this paper deals with an on-line drill wear monitoring system of the detection of tool wear with the computer vision and the area of the drill flank wear is analyzed quantitatively by the system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.888-891
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• 2000

Drilling is one of the most important operations in machining industry and usually the most efficient and economical method of cutting a hole in metal. From automobile parts to aircraft components, almost every manufactured product requires that holes are to be drilled for the purpose of assembly, creation of fluid passages, and so on. It is therefore desirable to monitor drill wear and hole quality changes during the hole drilling process. One important aspect in controlling the drilling process is drill wear status monitoring. With the monitoring, we may decide on optimal timing for tool change. The necessity of the detection of tool wear, fracture and the abnormal tool state has been emphasized in the machining process. Accordingly, this paper deals with the cutting characteristics of the hot-rolled high strength steels using common HSS drill. The performance variables include drill wear data obtained from drilling experiments conducted on the workpiece. The results are obtained from monitoring of the cutting force and Acoustic Emission (AE) signals, and from the detection of the abnormal tool state with the computer vision system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.83-88
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• 2017

Recently, the use of advanced materials with light weight significantly increases because of global regulation on CO2 emission. Especially, CFRP (carbon fiber reinforced plastics) one of the most promising advanced materials. Since CFRP has pretty higher strength per unit weight than steel, it is one of most popular materials in aviation industry and its application to automobile rises sharply. Especially, one of the frequent machining processes for CFRP is drilling to make a hole, however, CFRP drilling has troublesome limitations in hole quality and productivity induced due to delamination, splintering and severe tool wear. Particularly, cutting loads increase caused by tool wear makes delamination and splintering even severer. Therefore, tool wear monitoring or reduction in CFRP drilling must be considered seriously. In this study, we measured thrust force, flank wear, and tool surface temperature in drilling using various tools with different sizes and materials. Consequently, it was presented the effects of tool properties on drilled hole quality, thrust force and tool surface temperature.

• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.93-99
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• 1998

Lately public interest in tree saps of maple and birch trees stimulated to increase demands for sap drink as a natural medical beverage. In order to understand factors affecting tree sap flows, birch species, particularly Betula platyphylla in Mt.Sobaek area, were monitored for daily sap flows according to factors, such as DBH, tapping hole sizes and direction of hole drilling on the trunks. The chemical constituents of saps were also analyzed. The sap flow initiated from the end of March and finished at the end of April. The flow maxima appeared from April 14th to April 26th. Total amounts of the sap flow obtained from birch tree were over 1,800 ml per day per one tree. Sap flows were increased with increasing DBH and tree age. Six milimeter drilled hole resulted in the highest sap flows. Sap flows increased with increases of diameter and height of the trees. Hole drilling to downward side(south-facing) of tree produced almost doubled sap flows than that of upward one(north-facing), while rightside drilling produced same amounts of saps to that of leftside one. Six mm drilling gave the best results not only in maximum flows but also effective hole occluding rates. The saps have in the range of 4.5 to 5.6 pH and l.0 - 2.0% of saccharinity. Sucrose, glucose, fructose and high mineral contents were found in the saps of birch tree. The tree saps could be utilized not only medicinal drink, but also one of the healthy beverages.