• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1789-1794
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• 2003

As a new approach to analyze shear behaviors in the shear plane and chip-tool friction behaviors in the chip-tool contact region during an end milling process, this paper introduces a method to transform an end milling process to an equivalent oblique cutting process. In this approach, varying undeformed chip thicknesses and cutting forces in the up-and down-end milling process are replaced with the equivalent ones of oblique cutting. Accordingly, in the current paper, the shear and friction characteristics of end milling operations, up- and down-end milling, have been analyzed based on the equivalent oblique cutting models. Two series of cutting tests, up- and down-end milling tests and the equivalent oblique cutting tests to that, have been carried out to verify the validity of the analyses. And using the results of cutting tests the cutting characteristics of the up- and down-end milling processes have been thoroughly investigated.

• 한국재료학회지
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• 제11권12호
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• pp.1020-1027
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• 2001

Powder type Ag system insert metals were manufactured by mechanical alloying method. Alloying method was the ball milling process using zirconia ball media, and all alloying variables were constant except the milling time. The milling times were selected 24, 48 and 72 hours. The insert metals made by milling method were observed using scanning electron microscope and x-ray analyses. And also, the evaluation of wettability and microstructures of the insert metals were conducted to investigate the characteristics of the brazed joint. The wettability of the insert metals made by milling of 48 hours, was the best condition. And the insert metals contained Cd shows good wettability, however, there was the oxides residue on the brazing test specimen. The microstructures of the manufactured and the commercial insert metals were almost same displaying the Cu- rich proeutectic and Ag-rich eutectic. Further, there were some porosities. The 48 hours alloyed insert metal was exhibited the most sound brazed joint without containing porosity due to the superior wettability and good alloying condition.

• 대한기계학회논문집A
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• 제25권2호
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• pp.228-234
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• 2001

To obtain precise machined surface and high productivity in machining, high speed end milling has beed studied recently. Though high speed end milling is explicitly effective for precision surface generation geometrically, tool deflection, chatter vibration and frequency characteristics of end milling system deteriorate the theoretical surface. In this study, simulation algorithm and programming method are suggested to simulate machined surface using acceleration signal in high speed end milling. This simulation is conducted by considering vibrational effect of spindle system which was not considered by other investigators. Good agreements were obtained between simulated results and experimental results.

• Journal of Mechanical Science and Technology
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• 제14권6호
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• pp.622-632
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• 2000

In a high precision vertical machining center, the estimation of cutting forces is important for many reasons such as prediction of chatter vibration, surface roughness and so on. The cutting forces are difficult to predict because they are very complex and time variant. In order to predict the cutting forces of end-milling processes for various cutting conditions, their mathematical model is important and the model is based on chip load, cutting geometry, and the relationship between cutting forces and chip loads. Specific cutting force coefficients of the model have been obtained as interpolation function types by averaging forces of cutting tests. In this paper the coefficients are obtained by neural network and the results of the conventional method and those of the proposed method are compared. The results show that the neural network method gives more correct values than the function type and that in the learning stage as the omitted number of experimental data increase the average errors increase as well.

• 반도체디스플레이기술학회지
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• 제13권3호
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• pp.51-55
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• 2014

Ni-CNT(Carbon Nanotubes) composite coating is often used for the surface treatment of mechanical/electronic devices to improve the properties of the Ni coating. For the Ni-CNT coating, the dispersion of CNT fibers is a critical process. In this study, ultrasonic treatment instead of the conventional ball milling was attempted as a dispersion method for the electroless Ni-CNT coating. SEM-EDX analysis was performed and contact angle, sheet resistance, and micro-hardness were measured. Results showed that the ultrasonic treatment was comparable to the ball milling, as a dispersion method, but the difference was negligible. However, combined ball milling and ultrasonic treatment(double treatment) showed much improved micro-hardness value, above 350Hv(close to the value obtained by the Ni-CNT electroplating). In addition, electroless Ni-CNT(double-treated) coatings formed on the thin Ni film deposited by the electroless plating(double coating) showed better mechanical properties. Thus, double treatment and double coating are suggested as an improved electroless Ni-CNT coating method.

• Design & Manufacturing
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• 제14권2호
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• pp.56-61
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• 2020

Recently, research for machining next-generation micro semiconductor processes and micro patterns has been actively conducted. In particular, it is applied to various industrial fields depending on the machining method in the case of FIB (Focused ion beam) milling. In this study, intends to deal with FIB milling machining technology for ultra-precision diamond tool fabrication technology. Ultra-precision diamond tools require nano-scale precision, and FIB milling is a useful method for nano-scale precision machining. However, FIB milling has a problem of Gaussian characteristics that are differently formed according to the beam current due to the input of an ion beam source, and there are process conditions to be considered, such as a side clearance angle problem of a diamond tool that is differently formed according to the tilting angle. A series of process steps for fabrication a ultra-precision diamond tool were studied and analyzed for each process. It was confirmed that the effect on the fabrication process was large depending on the spot size of the beam and the current of the beam as a result of the experimental analysis.

• 한국정밀공학회지
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• 제17권8호
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• pp.46-52
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• 2000

3D Welding and Milling is a solid freeform fabrication process which is based on the combination of welding as additive and conventional milling as subtractive technique. This hybrid approach enables direct building of metallic parts with high accuracy and surface finish. Although it needs further improvements it shows an application potential in rapid tooling of injection mold inserts as the investigation results show. To optimize the process for higher surface quality and accuracy effectively Taguchi method is applied to the experimental investigation. in this way relationships between process parameters and final product qualities such as tensile strength and surface hardness are found with minimal efforts.

• Transactions on Electrical and Electronic Materials
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• 제16권2호
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• pp.53-61
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• 2015

High-energy ball milling was tested as a method for producing Ultra High Molecular Weight Polyethylene (UHMWPE)- based nanodielectrics containing 1 wt% and 5 wt% OctaIsoButylPOSS (OibPOSS). Qualitative and quantitative evaluations were used to explore the compatibility between OibPOSS and PE. Several ball milling variables were optimized in a bid to achieve UHMWPE/OibPOSS nanodielectrics. The morphology, as well as the thermal and the dielectric properties of the samples, were characterized by scanning electron microscopy, thermogravimetric analysis, broadband dielectric spectroscopy, and progressive-stress breakdown tests. The results showed that (i) ball milling was an effective method for producing UHMWPE/OibPOSS dielectric composites, but appeared ineffective in dispersing OibPOSS at the nanoscale, and (ii) the resulting UHMWPE/OibPOSS dielectric composites presented thermal and dielectric properties similar to those of neat UHMWPE.

• Carbon letters
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• 제15권3호
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• pp.180-186
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• 2014

This study highlights a novel method and mechanism for the rapid and effective milling of carbon fibers (CFs) in silicon carbide (SiC) powder, and also the dispersion of CFs in SiC powder. The composite powders were prepared by chopping and exfoliation of CFs, and ball milling of CFs and SiC powder in isopropyl alcohol. A wide range of CFs loading, from 10 to 50 vol%, was studied. The milling of CFs and SiC powder was checked by measuring the average particle size of the composite powders. The dispersivity of CFs in SiC powder was checked through scanning electron microscope. The results show that the usage of exfoliated CF tows resulted in a rapid and effective milling of CFs and SiC powder. The results further show an excellent dispersion of CFs in SiC powder for all CFs loading without any dispersing agent.

• 한국정밀공학회지
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• 제18권5호
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• pp.130-136
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• 2001

Generally, a metal slitting saw is plain milling cutter with thickness less than 3/16 inch. This is used for cutting a workpiece that high dimensional accuracy and surface finish is necessary. A small thin milling cutter like a metal slitting saw is useful for machining a narrow groove. In this case, built up edge(BUE) is severe at each tooth and affects the surface integrity of the machined surface and tool wear. It is well known that tool geometry and cutting conditions are decisive factors to remove BUE. In this paper, we optimized the geometry of the milling cutter and selected cutting conditions to remove BUE by the experimental investigation. The experiment was planned with Taguchi method based on the orthogonal array of design factors such as coating, rake angle, number of tooth, cutting speed, feed rate. Response table was obtained from the number of built-up edge generated at tooth. The optimized tool geometry and cutting conditions could be determined through response table. In addition, the relative effect of factors was identified bh the analysis of variance (ANOVA). Finally, coating and cutting speed turned out important factors for BUE.