• 한국기계가공학회지
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• 제11권6호
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• pp.69-74
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• 2012

Surface roughness is widely used as an index for processing degree of accuracy. Recently, regression analysis to predict the machining results are actively used to characterize a cutting operations. In the past, diamond machining had been used for ultra precision cutting operation, but now industrial diamond tools like PCD(Polycrystalline Diamond) have been widely used in ultraprecision machining of nonferrous metals. In this study, the authors focus on the effect of PCD tool property on the surface roughness of Al5083 aluminum alloy after cutting process by CNC operated lathe. Based on the regression analysis approach on a surface roughness data obtained by experiment, predictive analysis of surface roughness is effective to achieve better surface quality.

• 한국기계가공학회지
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• 제14권5호
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• pp.22-27
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• 2015

Processing of low toughness graphite material requires high-speed machine tools and DLC coating. In this study, results of investigation of the tool wear and machining properties of the DLC coating according to the thickness, and the machining time of the tool used for the machining of graphite electrodes, were as follows. 1. DLC coating thickness shows a larger wear amount of the tool center in accordance with thickness; the wear amount of the tool increases in proportion to the machining time. 2. The difference between the amount of wear depending on the processing time shows edge portions larger than the tool wear amount in the center. This amount of wear of the tool edge is formed since the rotating torque is in contact with the graphite material surface significantly more than the central portion. 3. The thicker the DLC coating, the more the coating tool eliminated of the coating area by the interface between the cemented carbide tool being coated with an increased friction of the graphite material and the DLC coating area.

• 한국정밀공학회지
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• 제9권2호
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• pp.61-68
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• 1992

To meet the requirements for accuracy, productivity and reliability of machine tools, it is necessary to evaluate the chatter-free machining performance and to improve the dynamic performance of machine tools. In order to perform dynamic design of machine tools reasonably and effectively, the joint parts must be modelled accurately because their characteristics affect significantly on the total characteristics of machine tool. In this paper, an approach which identifies the effect of joint parts on the performance of total machine tool structure was proposed. That uses the experimental modal analysis, the finite element method and the sensitivity analysis method. The effectiveness of this approach was confirmed by applying it to structures with bearing joints. And as a result of the application, the change of dynamic characteristics of bearing joints was indentified.

• 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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 Handout for 2000 Inter. Machine Tool Technical Seminar
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• pp.19-27
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• 2000

High speed machining (HSM), specifically end milling and ball end cutting, is attracting interest in the die/mold or aerospace industries for the machining of complex 3D surfaces. HSM of difficult-to-cut materials such as die/mold steels, titanium alloys or nickel based superalloys generates the concentrated thermal/frictional damage at the cutting edge of the tool and rapidly decreases the tool life. Following a brief introduction on HSM and reated aerospace or die/mold work, the paper reviews published data on the effect of cutter/workpiece orientation and cutting environments on tool performance. First, experimental work is detailed on the effect of cutter orientation on tool life, cutting forces, chip formation, specific force and workpiece surface roughness. Cutting was performed using 8 mm diameter PVD coated solid carbide cutters with the workpiece mounted at an angle of 45 degree from the cutter axis. A horizontal downwards cutting orientation proveded the best tool life with cut lengths ∼50% longer than for all other directions (horizontal upwards, vertical downwards, vertical upwards). Second, the cutting environments were investigated for dry, flood coolant, and compressed chilly air coolant cutting. The experiments were performed for various hardened materials and various coated tools. The results show that the cutting environment using compressed cilly air coolant provided better tool life than the flood coolant or the dry.

• Advances in materials Research
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• 제1권2호
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• pp.129-146
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• 2012

Polycrystalline diamond is an ideal material for parts with micro-holes and has been widely used as dies and cutting tools in automotive, aerospace and woodworking industries due to its superior wear and corrosion resistance. In this research paper, the modeling and simultaneous optimization of multiple performance characteristics such as material removal rate and surface roughness of polycrystalline diamond (PCD) with ultrasonic machining process has been presented. The fuzzy logic and taguchi's quality loss function has been used. In recent years, fuzzy logic has been used in manufacturing engineering for modeling and monitoring. Also the effect of controllable machining parameters like type of abrasive slurry, their size and concentration, nature of tool material and the power rating of the machine has been determined by applying the single objective and multi-objective optimization techniques. The analysis of results has been done using the MATLAB 7.5 software and results obtained are validated by conducting the confirmation experiments. The results show the considerable improvement in S/N ratio as compared to initial cutting conditions. The surface roughness of machined surface has been measured by using the Perthometer (M4Pi, Mahr Germany).

• 한국정밀공학회지
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• 제25권6호
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• pp.159-167
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• 2008

Cooling lubricants are used in machining operations in order to reduce friction at the tool-chip and tool-workpiece interfaces, cool both chip and tool, and remove chip. Furthermore, they influence a strong effect on the shearing mechanisms and, consequently, on the machined surface quality and tool wear. However, several researchers state that the costs related to cutting fluids is frequently higher than those related to cutting tools. Moreover, the cooling lubricants cause an increase in both worker's health and social problems related to their use and correct disposal. Therefore, many researchers have focused on the environmentally conscious machining technologies. One of the technologies is known as MQL(Minimum Quantity Lubrication) machining. In this paper, an experimental model to obtain the optimal cutting conditions in MQL turning was suggested, and the effects of cutting conditions on surface roughness and cutting force were analyzed. For these purposes, FFD (Fractional Factorial Design) and RSM (Response Surface Methods) were used for the experiment. Cutting force and surface roughness with different cutting conditions were measured through the external cylindrical turning of Al 6061 based on the experiment plan. The measured data were analyzed by regression analysis and verification experiments with random conditions were conducted to confirm the suggested experimental model.

• 한국기계가공학회지
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• 제15권4호
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• pp.134-140
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• 2016

Main Spindle System has effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, main spindle unit in Machine tools are often cases where damage occurs do not meet the design life due to driving in harsh environments. This is when excessive maintenance and repair of machine tools or for damage stability has resulted in huge economic losses. Therefore, this studying propose a method of accelerated life test for diagnosing and prognosis the state of life assessment main spindle system. Time status monitoring of diagnostic data - through the analysis of the frequency band signals were carried out inside the main spindle bearing condition monitoring and fault diagnosis.

• 한국정밀공학회지
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• 제24권2호
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• pp.33-40
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• 2007

In this study, presintered and full sintered low purity alumina ceramics were machined with various tools to clarify the effect of cutting fluid in machinability. The main conclusions obtained were as follows. When the presintered ceramics were wet machined with sintered diamond tool, the tool wear becomes extremely large, and higher cutting speed can be used than in the case of full sintered ceramics. The productivity of wet cutting with the sintered diamond tool is much higher than that of dry cutting. In the case of the CBN and ceramic tools, the tool wear were smaller at wet cutting than at dry cutting, especially exhibiting considerably larger grooved tool wear in wet cutting with ceramic tool.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.321-326
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• 2001

In the present study, $Si_3N_4-SiC$ ceramic composites that contained up to 20 wt% of dispersed SiC particles were fabricated via hot-pressing with an oxynitride glass. The microstructure, the mechanical properties, and the cutting performance of resulting ceramic composites were investigated. By fixing the composition as $Si_3N_4-20$ wt% SiC, the effect of sintering time on the microstructure, the mechanical properties, and the cutting performance were also investigated. For machining of gray cast i개n, the tool life increases with increasing the amount of SiC content in the composites; The tool life also increased with increasing the sintering time. The tool life of the home-made cutting tools was very close to that of commercial $Si_3N_4$ cutting tool. The superior cutting performance of $Si_3N_4-SiC$ ceramic cutting tools suggests the possibility to be a new ceramic tool material.