• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.12-15
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• 2002

In this paper, we fabricated a electro-chemical discharge machine for drilling microscopic glass hole. In this research, we used a glass plate and NaOH solution. From the experimental result, we knew that the change of voltage wave was caused by drilling microscopic hole of glass using electro-chemical discharge method. So, we can give a function of the power auto stop to electro-chemical discharge machine with the change of voltage wave.

• Structural Monitoring and Maintenance
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• v.6 no.4
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• pp.291-315
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• 2019

Fatigue cracks are inevitable in circumstances in which the cyclic loading exists. Therefore, many of mechanical components are in a risk of being in exposure to fatigue cracks. On the other hand, renewing the facilities or infrastructures is not always possible. Therefore, retrofitting the structures by means of the available methods, such as crack arrest methods is logical and in some cases inevitable. In this regard, this paper considers three popular crack arrest methods (e.g., drilling stop-hole, steel welded patch, and carbon fiber reinforced (CFRP) patch), which have been compared by using extended finite element method (XFEM). In addition, effects in terms of the width and thickness of patches and the configuration of drilling stop holes have been evaluated. Test results indicated that among the considered methods, CFRP patches were the most effective means for arresting cracks. Besides, in the case of arresting by means of drilling stop holes, drilling two holes next to the crack-tip was more effective than blunting the crack-tip by drilling one hole. In other words, the results indicated that the use of symmetric welded metal patches could lead to a 21% increase in fatigue life, as compared to symmetric stop holes. Symmetric CFRP patches enhanced the fatigue life of cracked specimen up to 77%, as compared to drilling symmetric stop holes. In addition, in all cases, symmetric configurations were far better than asymmetric ones.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.73-80
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• 1998

The identification of drilling joint dynamics which consists of drilling and structural dynamics and the on-line time series detection of malfunction process is substantial not only for the investigation of the static and dynamic characteristics but also for the analytic realization of diagnostic and control systems in drilling. Therefore, We have discussed on the comparative assessment of two recursive time series modeling algorithms that can represent the drilling operation and detect the abnormal geometric behaviors in precision roundshape machining such as turning, drilling and boring in precision diemaking. For this purpose, simulation and experimental work were performed to show the malfunctional behaviors for drilling operation. For this purpose, a new two recursive approach (Recursive Extended Instrument Variable Method : REIVM, Recursive Least Square Method : RLSM) may be adopted for the on-line system identification and monitoring of a malfunction behavior of drilling process, such as chipping, wear, chatter and hole lobe waviness.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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• pp.53-57
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• 2014

Thin glass (< 100 microns) is a promising material from which advanced interposers for high density electrical interconnects for 2.5D chip packaging can be produced. But thin glass is extremely brittle, so mechanical micromachining to create through glass vias (TGVs) is particularly challenging. In this article we show how laser processing using deep UV excimer lasers at a wavelength of 193 nm provides a viable solution capable of drilling dense patterns of TGVs with high hole counts. Based on mask illumination, this method supports parallel drilling of up over 1,000 through vias in 30 to $100{\mu}m$ thin glass sheets. (We also briefly discuss that ultrafast lasers are an excellent alternative for laser drilling of TGVs at lower pattern densities.) We present data showing that this process can deliver the requisite hole quality and can readily achieve future-proof TGV diameters as small $10{\mu}m$ together with a corresponding reduction in pitch size.

• 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 for Precision Engineering
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• v.15 no.6
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• pp.40-47
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• 1998

Drilling is an indispensable process in manufacturing of the die and mould and the other mechanical parts which needs high dimensional and surface accuracy. In this paper, a new type of drilling method was proposed in order to improve both processing efficiency and accuracy. Specifically, the helical motion using ball end mill tools, instead of normal drilling method, was applied to perform an effective hole machining. In this paper, an theoretical background of the new type of drilling method was established, and the feasibility of the proposed theory was proved by experiments, where proposed drilling process in the paper gave a different machining specification than general method did.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.115-121
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• 2008

A knowloedge of the residual stress distribution at circumferential welds can increase the prediction accuracy of a fracture assessment in pipe lines. In this study, in order to predict the residual stress distribution in the circumferential butt-welded pipes were measured, using the hole-drilling strain gauge method. Their practical applications were performed in to two kinds of pipes. As the results, the following characteristics were found. On the inner surface of pipes, the circumferential and axial residual stresses were both tensile near the center line of welding and both of them changed from tensile to compressive as the distance from the center line increased. On the outer surface, however, the circumferential residual stress was shown to be tensile wile the axial residual stress was compressive near the center line of welding, and later they were revered at the region far away from the centerline.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.79-83
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• 2001

A verification of multi-spindles drilling NC data is presented. The drilling of multi-spindles can offer productivity over three times as fast as that of single spindle. The most important things in machining tube sheet are precision of hole position and machining time. The drilling of multi-spindles has difficulties in controlling many motors to drive spindles and assign a correspondent number to each spindles. Multi-spindles drilling has different codes from CNC milling ; many subroutines, assignment of spindle, and so on. The conventional method, which inspects the NC code of the drilling, is to drill holes on a thin plate or tube sheet previously. The method results in low productivity because it consumed long machining time and welding for correction. This paper describes details of multi-spindles NC code and operation of multi-spindles drilling machine. A verification software of the multi-spindles drilling NC code is developed on the details.

• Laser Solutions
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• v.17 no.2
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• pp.5-10
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• 2014

Aluminum has been widely used in the electric applications because of light metals. When mechanical element is periodically moving with contacting other surfaces, the anodizing process for aluminum is useful for avoiding the abrasive damage. The anodized element has quietly different characteristics with respect to the distribution of hardness and crystal structure. In this work, the laser drilling of anodized surface is studied experimentally. Fusion drilling method - laser drilling with inert gas blowing - is used. The effect of various process parameters (gas pressure, laser power, focus position) is investigated with respect to the hole size and circularity.