• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.2
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• pp.6-12
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• 2015

In this study, the performance test was carried out under various operation conditions targeting four representing types of lubricant which are mostly used in nuclear power plants, and mutually compared the characteristic and performance of lubricant. Especially, introducing the concept of the thread friction coefficient (hereinafter, TFC), which makes the friction relation between the stem nut and stem screw dimensionless. The test was performed to compare the lubricant performance for the four kinds of lubricant (Texaco, Alvania, Mobilux, MOVLL). In a test of the room temperature stem, the TFC of MOV Long Life shows the lowest value, next to Alvania EP2, Texaco EP2, and Mobilux EP0 in that order. And in a test of the high temperature stem, the TFC of Texaco EP2 shows the lowest, next to MOV Long Life, Alvania EP2, and Mobilux EP0 in that order. From the test result of the aging condition, three types of lubricant (MOV LL, Texaco EP2, Alvania EP2) show similar patterns up to 36 months, but in 60 months, the TFC of lubricant are increased rapidly.

• Transactions of Materials Processing
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• v.10 no.7
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• pp.543-550
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• 2001

In order to find the effect of material property and lubricant viscosity on the frictional characteristics a sheet metal friction tester was designed and tensile test, surface roughness test, and friction test were performed with several kinds of drawing oils. Test results show that as the lubricant viscosity becomes lower, the friction coefficient is higher. When surface roughness is extremely low or high, friction coefficient is also high. Using these test results, the friction model considering lubricant viscosity and surface roughness is developed. The validity and accuracy of the friction model are shown by comparing the punch loads among FEM analysis results employing current friction model and conventional friction model respectively and experimental measurement.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.351-352
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• 2002

In this paper, studies were made on the palm oil methyl ester (POME) added lubricants using FT-IR for monitoring oil degradation. In order to assess the degradation characteristics of POME added lubricant by FT-IR, static oxidation test was conducted using three different blended lubricants (viz, zero percent POME, five percent POME and ten percent POME with mineral-based oil) for 280 hrs. The oxidation temperature was set at $140^{\circ}C$. FT-IR quantitative data indicate an increased in oxidation products which was formed from 10% POME added lubricants after 280 hrs of oxidation test. The 5% POME added lubricant and mineral-based lubricant (without POME) showed less oxidation product after the test. From the FT-IR spectrum analysis of the oxidized oils it could be concluded that 5% POME can improve the performance of mineral-based oil by forming protective films.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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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.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.991-996
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• 2001

This study is the manufacture of solid lubricant oilless bearing using sintered parts. PTFE was as organic solid lubricant and $MoS_2$ as inorganic solid lubricant, and its characteristics were studied. Thickness of lubricant was suited 25~$100\mu\textrm{m}$ for lubricant characteristics. Curring temperature of MoS_2$ film was 12$0^{\circ}C$, 2 hours and that of PTFE film was $260^{\circ}C$, 20 minutes. The solid weight and solid volume of $MoS_2$ film was 51.7% and 27.4%, and that of PTFE was 44.9% and 24.3%. Chemical resistant of PTFE solid lubricant oilless bearing was excellent as salt test was 520hours, and usable temperature range was $-200~+280 ^{\circ}C$. Conduction of electricity can be increase by addition of graphite or $$\alpha$- PbO_2$. The electric conductivity was 100~180$\Omega$.

• Tribology and Lubricants
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• v.27 no.1
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• pp.40-44
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• 2011

The object of this study is to investigate influences of supplied lubricant quantities on spur gear's pitting life. Pitting is a sort of contact fatigue failures and made by a repetitive load. Basically, pitting is difficult to predict its life by an analysis due to many factors to be considered about tribology problems. In this paper, pitting life was proved by experiment using two roller machine. For a contact fatigue test, operating circumstances should be considered. During the test, temperature and lubricant quantities are considered and to investigate an influence of lubricant quantities, a comparison between optimally enough and not enough lubricant quantity was implemented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.195-198
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• 2006

Zinc phosphate coating is required in nearly all steel cold forging operations. However, the chemical byproducts of this lubricant system are difficult to dispose of and have a negative environmental impact. In order to replace zinc phosphate based lubricants partially or completely, candidate lubricant has been developed in this study. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FEM 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. Three water-soluble lubricants; namely, Mec Homat, Royalcoat, and the developed lubricant were found to perform comparable to or better than zinc phosphate.

• Tribology and Lubricants
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• v.13 no.4
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• pp.47-52
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• 1997

Friction torques, electrical contact resistances and bearing temperatures were measured on high speed angular contact ball beatings for the spindle of machine tools. The test bearings ran with oil-air lubrication at the thrust loads from 320 N to 1920 N and at the rotational speed of up to 12000 rpm. Electrical contact resistances between balls and races were measured to evaluate the formation of the lubricant film in the contact area. The test results with sufficient lubrication showed that the variations of friction torques were sensitive to the thrust loads and the rotational speeds, and that the friction torques were higher than those with insufficient lubrication. With insufficient lubrication and high thrust loads, the collapse of the lubricant film was detected even at a high rotational speed. It was concluded that these high speed beatings to run in condition of fluid lubrication should require monitoring not only the temperature increase of the bearing but also the lubricant film formation in contact areas resulting from the change in the applied load and the lubricant amount.

• Transactions of Materials Processing
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• v.11 no.4
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• pp.349-354
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• 2002

In order to find the effect of lubricant viscosity, sheet surface roughness, tool geometry, and forming speed on the frictional characteristics in sheet metal forming, a sheet metal friction tester was designed and manufactured and friction test of various sheet were performed. Friction test results showed that as the lubricant viscosity becomes lower, the friction coefficient is higher. When surface roughness is extremely low or high, the friction coefficient is relatively high. The result also show that as the punch radius and punch speed becomes bigger, the friction coefficient is smaller. Using experimental results, the mathematical expression between friction coefficient and lubricant viscosity, surface roughness, punch comer radius, or punch speed is also described.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.24-27
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• 2001

Friction between the sheet and tools is one of the important factors affecting the sheet metal forming. Therefore, the clarification of the friction is essential to improve the formability of the sheet. In order to find the effect of material property and lubricant viscosity on the frictional characteristics, tensile test, surface roughness test and friction test are performed. The results showed that friction characteristics are mainly influenced by the surface roughness and lubricant viscosity. A mathematical model of the friction is developed for calculating friction coefficient in terms of surface roughness and lubricant viscosity. The validity and accuracy of the mathematical model of the friction are verified through the experiment and FEM analysis.