• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.133-138
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• 2002

The technique of high speed machining is widely studied in machining fields, because the high efficiency and accuracy in machining can be obtained in high speed machining. Unfortunately the development of tool fur high speed machining in not close behind that of machine tool. In this study, 10 types flat endmill is prepared for obtaining data according to tool shape. Especially, we concentrated in helix angle, number of cutting edge and rake angle. Cutting condition is selected for several experiments and measuring cutting farce, tool life, tool wear and chip shape according to cutting length. 3-axis cutting farces are acquired from the tool dynamometer with high natural frequency, as the conventional tool dynamometer (9257B, Kistler) has cannot measure the state of high frequency force. Particularly, we found out that the axial cutting force waveform has a good relation with tool wear features. And flow is interrupted at the beginning of cutting by the decrease of rake angle. By above results. it is suggested the endmill tool with 45$^{\circ}$helix angle, 6 cutting edge and -15$^{\circ}$rake angle is suitable for high speed machining.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.52-57
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• 2000

STD11 is one of difficult-to-cut materials and its cutting characteristic data is not built enough. A bad cutting condition of it leads to low productivity of die and mould, so it is necessary to evaluate the machining characteristics of STD11. In this paper, the relations of the geometry of ball-end mill and mechanics of machining with it are studied. The helix angle of ball-end mill varies according to a location of elemental cutting edge in the cutting process are difficult to calculate accurately. To calculate instantaneous cutting forces, it is supposed that the tangential, radial and axial cutting force coefficients are functions of elemental cutting edge location. Elemental cutting forces in the x,y and z direction are calculated by coordinate transformation. The total cutting forces are calculated by integrating the elemental cutting forces of engaged cutting edge elements. This model is verified by slot and side cutting experiments of STD11 workpiece which was heat-treated to HRC45.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.86-89
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• 2002

In NC machining, the ability to automatically generate an optimal process plan is an essential step toward achieving automation, higher productivity, and better accuracy. For this ability, a system that is capable of simulating the actual machining process has to be designed. In this paper, a milling process simulation system for the general NC machining was presented. The system needs first to accurately compute the cutting configuration. ME Z-map(Moving Edge node Z-map) was developed to reduce the entry/exit angle calculation error in cutting force prediction. It was shorn to drastically improve the conventional Z-map model. Experimental results applied to the pocket machining show the accuracy of the milling process simulation system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.259-260
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• 2013

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.26-32
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• 2019

Ball end mills used for high-speed and high-precision machining require longer machining time than flat end mills or face cutters, since the tool diameter is limited and the rigidity is reduced by the characteristics of the tool's cutting edge: at the top end of the tool, the cutting speed approaches zero and hardly removes any material. Because there is little material removal at the top end of the ball end mill, the outer cutting edge performs the majority of the work; this irregular cutting force deforms the tool and shortens its life. In this study, we attached an eddy-current sensor to a tool to measure the deformation from the cutting force and we used a tool dynamometer to measure the cutting force. We found that the change in cutting force is dependent on the change in feed rate during square-shaped processing and, as the feed rate is accelerated, the cutting force also increases. Higher cutting forces increase tool deformation.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.129-134
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• 2000

This paper presents the development of ultra-precision machining process of large aspheric aluminum mirrors with a maximum diameter of 620 mm. An ultra-precision machine, "Nanoturn60", developed by Daewoo Heavy Industries Ltd. is used for machining and motion errors of the machine are compensated by using the FTS developed by IAE(Institue for Advanced Engineering) during the machining process. To check the form accuracy of machined aspheric surfaces, on-machine form measurement system is developed. This measurement system consists of air bearing touch probe, straight edge, and laser sensor. With in-process error compensation by FTS(Fast Tool Servo), aspheric mirrors with the from accuracy of submicron order are obtained. obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.97-100
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• 2004

In recent years, a demand for micro-structure machining is increasing by the development of information and optics industries. Micro machining technology is in general well known in the field of lithograghy. However, the requirement of producing micro machine and/or micro mechanism with metal materials will be increased since a variety of workpiece configurations can be easily made. In this paper, ultra precision machine is developed to obtain micro groove and mirror surface using single crystal diamond tool. According to the cutting experiment, no burr was found at the edge of V-grooves, and the surface roughness of copper is about 1～3nm Ra. It is verified that ultra precision machine is effective to high precision machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.529-532
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• 2003

Machining technique for optical crystals with single point diamond turning tool is reported in this paper. The main factors influencing the machined surface quality are discovered and regularities of machining process are drawn. Optical crystals have found more and more important applications in the field of modern optics. Optical crystals are mostly brittle materials of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency. poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimum machining conditions for ductile cutting of optical crystals and apply the SPDT technique to the manufacturing of ultra precision optical components of brittle materials. As a result. the surface roughness is good when spindle speed is 200m/min. and teed rate is small. The influence of depth of cut is very small.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.284-291
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• 2013

Micro cutting of titanium alloy by polycrystalline diamond (PCD) tools was studied. Micro electro discharge machining (MEDM) was used to fabricate customized micro shaping tools from PCD blank. The tool was used to machine micro grooves on Ti alloy and the effects of depth of cut and machining length on tool wear, burr and surface roughness were studied. The shaping tool has cutting edge of a few ${\mu}m$. The crater size of the tool surface was increased with increasing capacitance of EDM machining conditions, which was used to control the surface roughness of the machined micro grooves.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.208-213
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• 2001

High speed milling(HSM) is one of the emerging cutting process having tremendous potential not only in increased metal removal rates but also in improved surface finish, burr free edge, dimensional accuracy and a virtually stress free component after machining. The High efficiency and accuracy in machining of die/mold materials can be obtained in high speed machining, so it is necessary to analytic the mechanism of high speed cutting process : cutting force, acoustic emission signal.