• 한국표면공학회지
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• 제43권1호
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• pp.41-45
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• 2010

The effect of $MoS_2$ and graphite content on wear resistance and mechanical properties of Cu/Sn bonded diamond micro blades was comparatively investigated in terms of volume and weight fraction. For the evaluation of endurance and cutting performance, instantaneous electric power consumption and cumulative wear loss during cutting glass work piece at constant velocity were measured with the micro blades of the wide range of lubricant content. The energy consumption of blades for glass cutting decreased with the content of lubricants. Wear amount of blade in volume increased with the amount of lubricant addition. It was found to be relevant to the decrease in flexural strength and hardness with the amount of lubricants. With the same amount of lubricant content in volume fraction $MoS_2$ showed superiority in mechanical properties and cutting performance than graphite while graphite could result in stronger effect on lowering electric consumption during cutting work piece for the same weight percent fraction than $MoS_2$ because of lower density.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.794-799
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• 2011

In order to reduce the oil consumption for a 2 stroke free piston hydrogen fueled engine, the behaviors of residual lubricant oil of the cylinder wall surface were visualized and oil mass emitted into exhaust port was measured by using research engine with cross-head and eccentric crankshaft. As the results, it was shown that characteristics of residual lubricant oil such as oil thickness and distribution were remarkably different from a conventional 4 stroke engine. It was also analyzed that these tendencies relied on the configuration and installed position of the exhaust port, piston pin boss and so on.

• 한국표면공학회지
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• 제41권6호
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• pp.335-340
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• 2008

Cutting performance and wear behavior were studied with the diamond micro-blade of Cu/Sn bond materials containing various amount of lubricant materials such as graphite and $MoS_2$. Measurement of instantaneous electric power consumption for cutting glass workpiece at the constant velocity was conducted and proposed as a method to assess cutting efficiency. The energy consumption of micro-blade for glass cutting decreased with the content of graphite and $MoS_2$ while wear amount of blade in volume increased with the amount of lubricant addition during the dicing test. It is because that hardness, flexural strength, and fracture toughness ($K_{IC}$) reduced with the amount of lubricant addition. Blades with $MoS_2$ additive showed higher mechanical properties than those with graphite additives when the same amount of the lubricant additive in wt.% was added. Due to the lower density of graphite than $MoS_2$, higher volume fraction of graphite could result in stronger effect on lowering electric power consumption by reducing the friction between blade and work piece however increasing wear rate due to the reduction in strength and fracture toughness. Adhesive wearing mode of micro blade could be remarkably improved by the addition of graphite as well as $MoS_2$.

• 한국기계가공학회지
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• 제13권2호
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• pp.35-40
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• 2014

Wire drawing is aplastic deformation process that produces a wire with a desired diameter by pulling the end of the wire through a die. During the cold wire drawing process, the temperature between the wire and the die bearing is increased. This temperature increase causesenergy consumption increase, bad wire quality, and decreased die life. To reduce friction and avoid high temperature between the wire and the die in the cold wire drawing process, a dry lubricant with soap particles is used. It is not possible to reused the lubricant onceiron oxide is attached to the soap particlesat high pressure die. In this study, recycling technologies for wasted soap particles with processes of crushing, separation, and screening are developed. From the evaluation, the recycling efficiency was found to be 86.97%.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.117-127
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• 1997

To maintain the reasonable temperature in the engine is very important to keep the steady combustion state of engine and to prevent increasing of lubricant consump- tion, deteriorating of lubricant, shortening of the life time of engine and decreasing of material strength. The method of energy balance for devided elements of radiator is considered to analyse the performance of radiator. Th data of engine test and vehicle cooling tunnel test are applied to program for calculation of radiator outlet temperature, and this result is compared with outlet temperature of vehicle cooling tunnel test. As a result, the radiator outlet temperature by numerical analysis agrees well with that by experiment. It is concluded that this simulation program is available in developing the cooling system for a new car.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.149-154
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• 2007

The zinc prosphate film treatments used to lubricating treatment of mostly cold forging processes. But there are several problems happened to lubricating treatment process such as happening harmful environment on person, complex lubrication processing occurring in energy and time consumption, eco-destructive and chemical by-product generation, the needs of waste disposal etc. As a result, a water-soluble lubricant was developed to replace the perfect or some of the zinc prosphate film in the world. In order to solve these problems, this study evaluated the performance of the typical water-soluble. In this study, for these requirement inquiry of two part. First, about possibility of replace zinc phosphate lubricant, quantitatively evaluation developed of water-soluble lubricant for cold forging vs zinc phosphate lubricant. Second, About optimization of coating Process use to equipment with practicable automatic coating Process. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FE code DEFORM, friction factor calibration curves, i.e. cup height ratio vs. punch stroke and spike height vs. punch stroke, were established for different friction factor values. By matching the cup height ratio and the punch stroke and spike height vs. punch stroke from experiment to that obtained from FE simulations, the friction factor of the lubricants was determined. Survey of comparative analysis use to SEM that sprayed lubricant surface structure of grain shape and characteristic of lubricant performance based on grain shape and deformed lubricant surface expansion. As a result, developed lubricant were found to perform comparable to or better than zinc phosphate. And thought this result, innovatively cope with generated problem of existing lubrication process.

• Tribology and Lubricants
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• 제34권6호
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• 한국응용과학기술학회지
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• 제34권1호
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• pp.12-24
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• 2017

현재 국내 엔진오일-윤활유가 배출가스에 미치는 영향에 대한 연구가 미비한 실정이며 그 실험 방법 또한 확립되어 있지 않다. 이에 엔진을 이용한 윤활유 성상 변화가 PM(Particulate Matters) 배출에 미치는 영향 평가방법을 수립하여 윤활유의 성상 및 열화가 자동차 성능과 환경성에 미치는 영향을 연구하고자 한다. 윤활유 소모 및 연소로 인한 DPF(Diesel Particulate Filter) 및 후처리 장치에 미치는 영향을 평가하는 것이 중요하며, 특히 DPF의 재생과정에서 생성되는 PM(Particulate Matters)과 Ash가 DPF에 미치는 장기적인 영향과 내부 변형 및 내구성에 대한 평가와 연구가 필요하다. 본 연구에서는 정형화 되지 않은 시험모드를 개발하였으며, 내구시험결과 High SAPs의 경우 Low SAPs(Sulfated Ash, Phosphorus and Sulfuate)보다 DPF내 Ash의 축적량이 많은 것을 확인하였으며, EGR(Exhaust Gas Recycling)의 Fouling 현상 가속화에 영향을 미칠 것으로 확인하였다. 본 연구결과물을 토대로 윤활유의 기유, 첨가제, 열화 등에 따른 엔진 및 차량의 성능과 배출가스 특성을 기술정책 자료로서 활용하도록 방향을 도모하고 시험 방법을 확립하고자 한다.

• Tribology and Lubricants
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• 제12권4호
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• pp.28-34
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• 1996

The lubrication characteristics of high-speed ball bearings have been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flow rates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 2969 N axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제24회 춘계학술대회
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• pp.86-93
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• 1996

The lubrication characteristics of high-speed ball bearings has been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flowrates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 303 kgf axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.