• International Journal of Fuzzy Logic and Intelligent Systems
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• 제5권3호
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• pp.183-188
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• 2005

Although it is widely used to find an optimum setting of manufacturing process parameters in a variety of engineering fields, the Taguchi method has a difficulty in dealing with multi-response situations in which several response variables should be considered at the same time. For example, electrode wear, surface roughness, and material removal rate are important process response variables in an electrical discharge machining (EDM) process. A simultaneous optimization should be accomplished. Many researches from various disciplines have been conducted for such multi-response optimizations. One of them is a fuzzy logic approach presented by Lin et al. [1]. They showed that two response characteristics are converted into a single performance index based upon fuzzy logic. However, it is pointed out that information regarding relative importance of response variables is not considered in that method. In order to overcome this problem, a desirability function can be adopted, which frequently appears in the statistical literature. In this paper, we propose a novel approach for the multi-response optimization by incorporating fuzzy logic into desirability function. The present method is illustrated by an EDM data of Lin and Lin [2].

• 한국기계가공학회지
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• 제13권4호
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• pp.1-6
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• 2014

The specular hologram is one type of hologram, and it consists of many arcs. They are very easy to fabricate and can even be machined by hand and a compass. In this study, we designed two squares having different depths and consisting of many arcs, after which we machined the arcs using end-mill technology. The width of the machined arcs showed high repeatability. Moving tracks were observed on the bottom surface, and top burrs were noted. In spite of them, the phenomenon of the specular hologram was observed when an observer and a light source stood on the same side. The two squares seemed to have different depths when they were observed from the left and right directions. In this study, it was verified that a specular hologram can be manufactured by end-mill technology.

• 한국기계가공학회지
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• 제12권6호
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• pp.23-29
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• 2013

In this paper, pure $I_{ph}$ and hybrid carbon nanotube reinforced $I_{ph}$ were sintered using the SPS(spark plasma sintering) method for high densification. A nanosecond laser (${\lambda}=1063nm$, ${\tau}P=10ns$) and a femtosecond laser (${\lambda}=1027nm$, ${\tau}P=380fs$) were installed on an optical system for the micromachining test. The ablation characteristics of the pure $I_{ph}$ and CNT/$I_{ph}$ composites, such as thermal effect and ablation depth, were investigated using FE-SEM and a confocal microscope device. Laser machining results for the two mating materials showed improved performances: CNT/$I_{ph}$ composites showed good surface morphology of hole drilling without a melting zone due to the composites' high thermal properties; also, the ablated depth of CNT/$I_{ph}$ was higher than that of pure $I_{ph}$.

• 대한기계학회논문집A
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• 제33권7호
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• pp.621-628
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• 2009

Nickel-phosphorus alloys are attractive materials for diamond turning applications such as fabrication of large optics and other high precision parts. It is also well-known that the higher phosphorus content of the alloys minimizes the diamond tool wear. Due to the weakness of electoless nickel plating that the phosphorus contents is limited to 13-14% (wgt), increased attention has been paid at electro-nickel plating which enables the alloys with 15-16% phosphorus. In this study, experiments were carried out to observe the wear characteristic of single crystal diamond tools in micro-grooving of electro-nickel plated drums. The experiments shows that long distance (50km) machining of micro-grooving on electro-nickel plated drum is possible with a single crystal diamond tool without any significant tool wear and defective machined surface.

• 산업기술연구
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• 제31권A호
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• pp.45-51
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• 2011

A study has been made on defects which are formed in manufacturing processes of engine bearing and also on fatigue crack growth behavior in each step of bearing metal manufacturing. After the first step (sinter brass powder on steel plate ; Series A) many voids are made on brass surface and its size is decreased at the second step (rolling process of sintered plate ; Series B). After the third step (re-sintering step of brass powder and rolling ; Series C) the number of voids is decreased and its type shows line. The time of fatigue crack initiation and the growth rate of fatigue crack are in order of Series A, Series B, Series C. These reasons are that void fosters the crack initiation and growth, and residual stress made by rolling process affects on the crack growth rate in Series B, C. In forming and machining processes by use of final bearing metal, crack was observed at internal corner of flange and peeling off was observed at interface between steel and brass. Owing to the above crack and peeling off, it is considered that there is a possibility of fatigue fracture during the application time.

• 대한산업공학회지
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• 제29권1호
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• pp.21-31
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• 2003

Determination of operational dimensions and tolerances is complex if there exist inconsistencies between operational and design specifications. Dimension and tolerance charts (D&T charts) have been used to establish the relationships among operational dimensions in complex machining. This chart proves that individual operations can be harmonized when they are interconnected. However, it is hard to generate the chart manually. Because operational dimensions and tolerances must meet the design specifications, the dimensions and tolerances of interconnected operations have to be verified serially for economical operations. In this paper, the chart is automatically generated from the interconnected operations. More importantly, all operational dimensions and tolerances displayed in the chart have been verified by using LP to meet the design specifications. Finally, the chart is converted to an operational routing sheet that contains a detailed process plan along with cutting speed, feed rate, and operational references based on material hardness, surface finish, and tool nose radius.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.401-402
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• 2006

All-surface, all-tooth machining and roll forming of cast iron have been used to manufacture the crankshaft position sensor wheel (CPSW). However, these methods pose many problems such as difficult processing, high material cost, and low tooth precision. Thus, we developed a sintered CPSW with an improved detection ability in order to resolve the problems related with the previous methods of manufacturing CPSW by simplifying the process flow and improving tooth precision. The sintering process is introduced in this study. We conducted an experiment to compare the sintered and roll formed products and analyzed the results to evaluate the reliability of the sintering process. Furthermore, we compared and analyzed stress and displacement in the sintered and roll formed products through the "Finite Element Method(FEM)". According to the experimental and FEM results, the sintered product showed satisfactory mechanical properties. It was less expensive to process and lighter and showed better quality than the roll formed product. The results of this study could be applied to design an optimum CPSW using the sintering process.

• 한국레이저가공학회지
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• 제18권1호
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• pp.7-11
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• 2015

In this paper, micro trench structure is fabricated by femtosecond laser for inserting optical reflecting wavelength filter in planar waveguide. The width and depth of the trench is controlled by femtosecond laser machining condition. Also, large scale of single channel with 500um and 1000um on silica plate is fabricated by femtosecond laser, and roughness of the channel surface is polished by $CO_2$ laser for the insertion of the filter. Then, the characteristic of the planar waveguide inserted the filter is verified.

• 한국항행학회논문지
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• 제17권5호
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• pp.574-580
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• 2013

본 논문에서는 박막코팅기술의 공정은 고경도 박막과 질화층의 접합력을 높이기 위하여 적용하였다. 이 박막코팅기술은 프레스 금형에 사용되는 경도와 인성을 얻을 수 있는 복합 박막을 형성했다. 이러한 박막 코팅 생산 기술은 물리증착방법을 이용하여 진공 챔버의 진공도를 증가하고, 건파워의 투사율을 향상시켰다. 티타늄합금 타겟은 각종 정밀가공 부품에 복합박막코팅기술 개발을 통하여 성능과 표면재질을 개선하였다.

• 한국기계가공학회지
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• 제20권2호
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• pp.86-92
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• 2021

Usually, the die-cast components used in small mobile devices require finishing processes, such as computer numerically controlled coating. In such cases, porosity is the most important defect. The shape of the molten aluminum that passes through the runner and gate in a mold is the one of the factors that influences gas porosity. To define the spurt index, which numerically indicates the shape of molten aluminum after the gate, Reynolds number and Ohnesorge number are used. Before die fabrication, computer-aided engineering analysis is performed to optimize the filling pattern. Finally, X-ray and surface inspection are performed after casting and machining to evaluate how the spurt index affects porosity and other product parameters. Based on the results obtained herein, a new gating system design process is suggested.