• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.48-52
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• 1995

Chipping is an unavidable phenomean in the slot grinding process of hard and brittle materials. However,it should be reduced for the improvement of surface integrity in the manufacture of optical and semiconductor components. Electrolytic In-process Dressing (ELID) technique for metal bonded superabrasive grinding wheel has been developed for mirror surface grinding of hard and brittle materials. Electrically dressed wheel surface has sharply exposed abrasives and results in lower grinding force, higher grinding efficiency in grinding. The paper deals with a newly developed method for slot grinding using ELID and was implemented to improve grooved surface quality and decreases chipping size on the edge of the groove. As a result, we accomplished shipping-free grooves and obtained the clear ground sufaces on glass and tungsten carbide.

• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.136-143
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• 2008

This paper presents the application of a robot which aims at grinding automatically welding-bead remained in the removal job of working pieces for shipbuilding. In specific, the investigation on this application is composed of two parts; one topic is on the development of a robot platform vertically movable on a steel plate of hull, while the other topic is of the development of a grinding tool mechanism in order to remove welding-beads by using a diamond wheel installed on a servo cylinder (which can result in high working pressure on the grinding wheel). Besides, the development of a vision system for tracking welding-beads as well as recognizing welding surfaces is added for the convenience of this robot application to the removal of welding-beads remained in the working pieces for shipbuilding.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.5
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• pp.42-55
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• 1994

Presently, abrasive processing is on eof several methods for cutting and grinding brittle materials, and high quality in dimensional accuracy and surface roughness are often required as a structural components, therefore most of them has to be ground. In manufacturing of tungsten-carbide components, grinding by diamond wheel is usually adopted in order to provide configurational and dimensional accuracy to the components. The present study proposes the experi- mental research of optimum condition to the high quality surface grinding of the WC-Co material using diamond abrasive wheel in order to minimize the damage on the ground surface and to pursue the precise dimension by conventional grinding machine. Brief investigation is carried out to decrease the dressing is constant, theoretical grinding effect such as machining precision is changed according to the speed of workpiece. Accordingly, normal and tangential grinding forces, which are Fn, Ft were analyzed for the machining processes of WC-Co material to obtain optimum grinding conditions, 3-point bending test is carried out to check machining damage on the ground surface layer, which is one of sintered brittle materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.39-43
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• 1996

This paper described on the effect of residual stocks in internal grinding of tungsten carbide materials in order to improve the grinding efficiency as well as grinding accuracy. Though the fundamental investigation is carried out for tungsten carbide materials using electroplated diamond wheel, the residual stock after grinding process is effective to the grinding effciiency. The obtained results are as follows: (1) Under the depth of cut(t) is constant and decreasing the workpiece velocity(Vw), the resiudal stock after grinding is increased, but the difference is little less than the difference by table speed. (2) Increasing the wheel velocity, the residual stock after grinding is decreased. Therefore in order to minimize the residual stock, the wheel velocity should be increased as far as possible. (3) The surface foughness and out-of roundness increased with depth of cut and table speed, and decreased with wheel velocity, but it may as well adopt as much as polssible under the dimensional tolerance which is required for high efficiency grinding. (4) In order to remove residual stock, the spark-out grinding shoule be done, and it also can be improved about 20 .approx. 25% throughout spark-out grinding, and the number of optimal spark-out times were within 10 times.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.41-46
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• 2019

The purpose of this study is to examine and propose a high quality blade manufacturing method by applying ELID grinding technology to machining the tungsten carbide blade edge for MLCC sheet cutting. In this study, experiments are performed according to the abrasive type of grinding wheel, grinding method and grinding direction using the non-stop continuous dressing ELID grinding technology. By comparing and analyzing the chipping phenomena and surface roughness of both the blade grinding surface and the processed surface, a method for machining the tungsten carbide blade for cutting MLCC sheet is proposed. From the analysis of the surface roughness and chipping phenomena, it is confirmed that the use of diamond abrasive is advantageous for the blade machining. In addition, it succeeds in the machining of $6{\mu}m$ fine blade without any chipping, by using the grinding wheel #4000 with the diamond abrasive.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2514-2522
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• 1994

The mirror surface grinding of carbon fiber reinforced plastics(CFRP) was realized by using the metal bonded super-abrasive micro grain wheel with electrolytic in-process dressing(ELID). The maximum surface roughness $R_{max}$ of CFRP which was obtained with #6,000 wheel, was 0.65 $\mu{m}$, which was rougher surface finish compared to those of hard and brittle materials with the same mesh number wheel with ELID. The grinding performance was much dependent on the grinding direction and the best surface roughness was obtained at $90^{\circ}C$ grinding with fiber direction. The spark-out effect on the surface improvement was significant when smaller mesh number grinding wheels were used. From the surface observations of CFRP with scanning electron microscope(SEM) and Auger electron spectroscopy(AES), it was found that the mirror surface grinding of CFRP was generated by the homogenization due to carbonization of the ground surface and smearing of chips composed of the carbon fiber and carbonized epoxy resin into the ground surface.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.178-189
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• 1993

Engineering ceramics have some excellent properties as the material for the mechanical components. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this paper experiments are carried out to obtain the effect of "In-process dressing" to grind the Engineering ceramics with high efficiency. To save running time for dressing process and obtain restraint effect of diamond grain wear, "In-process dressing" system usint WA stick type honing stone is proposed. Representative High Strength Engineering ceramics A1$_{2}$O$_{3}$ and Si$_{3}$N$_{4}$are ground with diamond wheel. Also bending strengrh test is carried out to check upward tendancy of mecahnical properties as the result of machining defact restraint through the grinding maching method using "In-process dressing" process. Some results obtained in this study provide useful information to attain the high efficency grinding and the high mechanical properties of Engineering ceramics.rties of Engineering ceramics.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.4
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• pp.9-16
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• 2003

In this study, the decision of dressing time for diamond wheel was analyzed by observing with acoustic emission signals and surface roughness, and also obtained the machining characteristics by weibull distribution plot for the values of bending strength. From the experimental study, it was possible to predict the time of re-dressing for the diamond grinding wheel with the analysis of acoustic emission signals and surface roughness values, and following conclusions were obtained. The root-mem-square values of acoustic emission signals were obtained low as the increased of table speed for different abrasive grain size. This is caused by the lack of grinding power which is not able to get rid of all real grinding mass of depth as the table speed is increased. The values of bending strength for ground $Si_3 N_4$ specimens were decreased for gain size of #400 than that of #60, but it was found that the surface roughness values for gain size of #60 were better than that of #400. As compared the shape parameter of weibull distribution plot for the values of bending strength, it was found that the reliability of bending strength for grain size of #60 increased than that of #400.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.105-112
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• 1990

Advanced ceramics have some excellent properities as the material for the mechanical component. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this paper, some experiments are carried out to find the basic grinding characteristic of advanced ceramics. Representative advanced ceramics, such as AL/sub 2/ O/sub 3/, ZrO/sub 2/, SiC and Si/sub 3/N/sub 4/and ground with diamond wheels. Special attention is paid to comparison between the conventional and creep feed grinding. Results obtained in this study provide some useful informations to attain the high efficiency grinding of advanced ceramics.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.26-26
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• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis methods. The effectiveness of the grinding prediction model was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment details, the results and implications are presented.