• Journal of the Korean Society for Precision Engineering
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• v.1 no.2
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• pp.41-46
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• 1984

The machinability of calicium-deoxidized steel is studied in turning by being compared with that of Fe-Si deoxidized steel under a given set of cutting condition. Tool life, cutting force and cutting mechanism are examined on a few sorts of steel. It is found that adhesive layer "Belag" is developed on the cemented carbide tool and the peak value is observed at the cutting speed of 300m/min followed by gradual increase in the thickness of Belag with the increase of cutting speed. the maximum thickness of Belag is also shown at the feed of 0.3mm/rev. On the other hand, the tool life of carbide tool is more favorable than that of high speed steel (SKH 9) in cutting calcium- deoxidized steel. It is considered that the steel deoxidized with Ca-Si shows better machinability a little than that with Fe-Si. However, the cutting force and the shear angle of the former are similar to those of the latter in turning.n turning.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.270-276
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• 2000

Hard turning has the potential to replace grinding process and to achieve significant reduction in production time and cost. The main applications for hard turning is finishing process, namely grinding process. Therefore, it must be able to satisfy high surface integrity of the workpiece. This paper discusses surface quality in terms of residual stress and damaged layer with respect to cutting parameters in an intermittent hard turning. Damaged layer experiment is carried out orthogonal array. From that is based on the orthogonal array. From the response table, cutting parameters are analyzed from the view point of the damaged layer and residual stress. From this experimental results, even though in the intermittent hard turning, surface integrity turns out be good enough for replacing grinding process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.176-180
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• 2002

All types of VLM-s process include the linear heat cutting of EPS foam to generate a layer with 3D shape. The dimensional accuracy and part quality of the cut part are dependent on the thermal characteristics in the EPS foam. The thermal characteristics are determined by operating parameters such as an effective heat input and cutting angle. The objective of this study is to investigate into the influence of cutting angle on the kerfwidth and the melted length of the cut part using the numerical analysis and the experiments in generally sloped cutting with two cutting angles. In order to estimate an accurate temperature field, the transient thermal analysis using moving coordinate system, the fully conformed mesh and the heat flux model with two cutting angles is carried out. From the results of the analysis and the experiments, it has been found that the influence of the rotational angle about x-axis in which the rotational axis is normal with hotwire cutting direction is appreciably negligible in comparison with that of the rotational angle about y-axis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.11-14
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• 2001

In all Rapid Prototyping(RP) processes, computer-aided design(CAD) solid model is sliced into thin layers of uniform, but not necessarily constant, thickness in the building direction. Each cross-sectional layer is successively deposited and, at the same time, bonded onto the previous layer, the stacked layers form a physical part of the model. The objective of this study is to develop a method for obtaining necessary coordinates$(x,\;y,\;\theta_x,\;\theta_y)$ to position linear hotwire of the cutting system in three-dimensional space for the Variable Lamination Manufacturing process (VLM-S), which utilizes expandable polystyrene foam sheet as part material. In order to examine the applicability of the developed method to VLM-S, various three-dimensional shapes, such as a spanner, a patterned columm, and a pyramid were made using data obtained from the method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.883-886
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• 1997

In all Rapid Prototyping (RP) processes, a CAD solid model is sliced ito thin layers of uniform, but not necessarily constant, thickness in the building direction. Each cross-sectional layer is successively deposited and, at the same tim, bonded onto the previous layer; the stacked layers form a physical part of the model. The objective of this study is to develop a methode for calculating the rotational angle(θ/sub x/, θ/sub y/) of the linear hotwire cutting system in the three-dimensional space for the Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-S). In order to examine the applicability of the developed method to VLM-S, various three-dimensional shapes, such s a screw, an extruded cross, and a figure of Sonokong, were made using the data obtaiend from the method.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.147-155
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• 2000

To reduce the noise from wood cutting saw at the saw mill(lumber mill) or a construction area, some multi-layer sandwich saw blades which a aluminum or copper plate was inserted between the two steel plates were developed and were tested of the wood cutting noise level at various test places. From the research, it was found that the multi-layer saw blade with copper or aluminum plate between steel plates and spot welded 60 points could reduce the wood cutting sound level about 8.3 dB(97.031 dB - 88.743 dB) at indoor test and 3.8 dB(84.805 - 81.638 dB) at field test.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.9-17
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• 2010

The FPCB is used for electronic products such as LCD display. The process of manufacturing FPCB includes a cutting process, in which each single FPCB is cut and separated from the panel where a series of FPCBs are arrayed. The most-widely used cutting method is the mechanical punching, which has the problem of creating burrs and cracks. In this paper, the cutting characteristics of the FPCB have been experimented using Nd:YAG DPSS UV laser as a way of solving this problem. To maximize the industrial application of this laser cutting process, test samples of the multilayered FPCB have been chosen as it is actually needed in industry. The cutting area of the FPCB has four different types of layer structure. First, to cut the test sample, the threshold laser cut-off fluence has been found. Various combinations of laser and process parameters have been made to supply the acquired laser cut-off fluence. The cutting characteristics in terms of the variation of the parameters are analyzed. The laser and process parameters are optimized, in order to maximize the cutting speed and to reach the best quality of the cutting area. The laser system for the process automation has been also developed.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.519-526
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• 2017

In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.34-39
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• 2003

The paper will present chip formation mechanism and surface integrity generation mechanism based on the systematical experimental tests. Some basic factors such as the end milling cutter tooth number, cutting forces, cutting temperature, cutting vibration the chip status, the surface roughness, the hardness distribution and the metallographic texture of the machined surface layer are involved. The chip formation mechanism is typical thermal plastic shear localization at high cutting speed with less number of shear ribbons and bigger shear angle than that at low speed, which means lack of chip deformation. The high cutting speed with much more cutting teeth will be beneficial to the reduction of cutting forces, enlarge machining stability mot depression of temperature increment anti-fatigability as well as surface roughness. The burrs always exist both at low cutting speed and at high cutting speed. So the deburring process should be arranged for milling titanium alloy in my case.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.599-602
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• 2002

A novel rapid prototyping (RP) process, an automated transfer type variable lamination manufacturing process (Automated VLM-ST) has been developed. In Automated VLM-ST, a vacuum chuck and linear moving system transfer the plate type material with two pilot holes to the rotation stage. A four-axis synchronized hotwire cutter cuts the material twice to generate Automated Unit Shape Layer (AUSL) with the desired width, side slopes, length, and two reference shapes in accordance with CAD data. Each AUSL is stacked on the stacking plate with two pilot pins using the pilot holes in AUSL and the pilot pins. Subsequently, adhesive is supplied to the top surface of the stacked AUSL by a bonding roller and pressure is simultaneously applied to the bottom surface of the stacked AUSL. Finally, three-dimensional shapes are rapidly fabricated. This paper describes the procedure for generating the cutting path data (AUSL data) f3r automated VLM-ST. The method for the generation of the Automated Unit Shape Layer (AUSL) in Automated VLM-ST was practically applied and fabricated for a various shapes.