• Korean Journal of Materials Research
• /
• v.18 no.12
• /
• pp.635-639
• /
• 2008

In this paper, experimental studies of the regrinding of tungsten carbide (WC-Co) tools for high-speed machining were conducted. Regrinding and a subsequent evaluation test were carried out for a flat endmill tool with diameters of 10 mm and 3 mm using a CNC five-axis tool grinder and a CNC three-axis machining center. Tool wear on the two types of endmill tools increased as the cutting length increased, and the tool wear was not influenced by the regrinding state. In case of the micro endmill with a tool diameter of 3 mm, the effective regrinding time was determined for a flank wear threshold of 0.3 mm considering the tool life according to cutting length. The tool lives of the 10 mm and 3 mm endmill tools were increased by 80% and 72%, respectively. This conclusion proves the Feasibility of the recycling of tungsten carbide materials in the high-speed machining of high-hardened materials for industrial applications.

• Industrial Engineering and Management Systems
• /
• v.9 no.3
• /
• pp.242-250
• /
• 2010

For economical and environmental reasons, the aim of this research is hence to monitor the cutting conditions with the dry cutting, the wet cutting, and the mist cutting to obtain the proper cutting condition for the plain carbon steel with the ball end milling based on the consideration of the surface roughness of the machined parts, the life of the cutting tools, the use of the cutting fluids, the density of the particles of cutting fluids dispersed in the working area, and the cost of cutting. The experimentally obtained results of the relation between tool wear and surface roughness, the relation between tool wear and cutting force, and the relation between cutting force and surface roughness are correspondent with the same trend. The phenomena of surface roughness and tool wear can be explained by the in-process cutting forces. The models of the tool wear with the cutting conditions and the cutting times are proposed to estimate the tool cost for the different cooling strategies based on the experimental data using the multiple regression technique. The cutting cost is calculated from the costs of cutting tool and cutting fluid. The mist cutting gives the lowest cutting cost as compared to others. The experimentally obtained proper cutting condition is determined based on the experimental results referring to the criteria.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.33 no.9
• /
• pp.1506-1518
• /
• 2009

This study identifies the relationships among demographic variables, well-being health consciousness, sports/leisure activity, and the perceived premium price for high functional sports/leisure wear. An empirical study was conducted with the data collected by questionnaires distributed to male and female respondents aged 15 and over. Descriptive statistics, factor analysis, MANOVA, two-way ANOVA, and regressions were used to analyze 244 answers. As a result, 3 factors were determined for well-being health consciousness: nature-friendly life, premium consumption for health, and health care. The older group pursued a nature-friendly life more than the younger group, the female group pursued premium consumption for health more than male group, and older women and younger men pursued health care more than their counterparts. Sports/leisure activity was relatively intensive in the male group and in the younger group. Sports/leisure activity was explained by male characteristic and health care factors. Sports/leisure activity was the only element for predicting the perceived premium price ratio for high functional sports/leisure wear.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.4
• /
• pp.677-682
• /
• 2002

Break-in is an intentional treatment to enhance the performance life of machinery parts and to maintain static friction behavior. Most studies on break-in have concerned only about surface conditions such as roughness or film formation. But the exact mechanism of break-in has not been found yet. Friction, scuffing behavior and wear of AISI 1045 were studied in relation to break-in and residual stress. The cylinder-on-disk type tribometer was used with the line-contact geometry. Scuffing tests were carried out using a constant load of 730N. In the break-in procedure the step load was applied from 100N to 200N. In this experiment, it was found that the break-in helps compressive residual stress to be formed well enough to enhance the scuffing life during the scuffing test. Specimens that had high compressive residual stress induced by shot-peening show better wear resistance than those were not shot-peened. Results of scuffing test, break-in procedure and wear amount in relation to residual stress have been discussed.

• Tribology and Lubricants
• /
• v.22 no.4
• /
• pp.211-217
• /
• 2006

Ring and groove wear may not be a problem in most current automotive engines. However, a small change in ring face and groove geometry can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each part's wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of rings and grooves are obtained from three engines before and after engine durability test. The calculated wear data of each part are turn out to be at the lower bound of aver-aged test values or a little below.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.10
• /
• pp.873-878
• /
• 2016

SCM415 steel for the control valve undergoes wear because of continuous movement between the valve and valve case. The wear of the valve interrupts the performance of the valve, and decreases the service life. In this study, wear characteristics of the as-received and carburized SCM415 steels are evaluated. The wear tests are conducted for various temperatures and loads using a reciprocating wear tester. From these results, wear loss, specific wear rate, and coefficient of friction are analyzed. The wear mechanism was analyzed by SEM. The interaction effects between loads and temperatures on wear loss are determined for analysis of variance using MINITAB.

• Journal of Fashion Business
• /
• v.12 no.1
• /
• pp.76-92
• /
• 2008

The purpose of this study was to analyze the general wearing attitude & brand Image Perception for Golf Wear in wearer's mind, and to investigate the brand preference on the image characteristics of golf wear, and to find out the wearer's purchasing point for golf wear, for developing the possibility and strategy of the golf wear market for the apparel marketers and manufacturers. For this study, the data obtained from 210 respondents were analyzed by the descriptive statistics, Pearson's simple correlation, Crossing Analysis, parato graph. The results from the study were as follow : The respondents who were specially wearing for golf game were 23.3%(49 persons) among the 210 respondents. The 210 respondents evaluated highly the features of golf wear, such as design(51%), quality(44.3%), materials(36.2%), color(35.2%), size(21.0%), as the purchasing point for golf shirts, otherwise, the 210 respondents evaluated lowly the social aspects of golf wear, such as, fashion conformity, brand loyalty and promotion. And the most important material features for the golf wear was the elasticity, speed dryness by the 210 respondents The most frequent brand by 207 respondents described in the free style was Daks(11.1%) and Ping(11.1%). The 205 respondents described in the free style evaluated Daks(14.6%) as the most preference brand. The reason for the most preference brand was based with the comfort and pleasure of design, quality, color, size, materials.

• Journal of the Korean Society for Precision Engineering
• /
• v.2 no.1
• /
• pp.62-71
• /
• 1985

This is a study on the monitoring technique in tool failure and tool life by AE method. The relation between amplitude level of AE signal and flank wear width was studied by experiments. The relation between amplitude level of AE signal and tool life was also studied. As the result, it was observed that amplitude level of AE signal was only affected by cutting velocity. Amplitude level of AE signal was directly proportional to flank wear width and the increasing rate was related to cutting velocity. So, the relation between amplitude level of AE signal and tool life was represented as follow: $CT^n$ = $AE_{rms}$ where, n=0.35 C=9.5*$10^{-2}$

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.1 no.1
• /
• pp.101-108
• /
• 2002

In the grinding process, the degree of the sharpness in wheel gram affects the surface roughness and the dimensional accuracy. If a wheel with dull grains is used, the grinding force will be increased and the surface roughness deteriorated. To produce a precision component, the magnitude of parameters related to the wear amount of a grinding wheel has to be limited. In this study, a variation of the grinding force and the surface roughness were measured to seek the machining characteristics of the W A and CBN wheels. From the wear amount of the grinding wheel and the removal rate of workpiece, the grinding ratio was calculated. And also the wheel life was determined at a rapid decreasing point of the grinding ratio. The difference between the surface of wheel-workpiece before grinding and after wheel life was clearly verified with a microscopic photo.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.39-46
• /
• 2005

In this study, unsintered, presintered and full-sintered low purity alumina ceramics were machined with various tools to clarify the machinability and the optimum cutting conditions. The main conclusions obtained were as follows. (1) Machined with alloy steel tool, the machinability of the presintered ceramics becomes better with the decrease of presintering temperature, but that of unsintered ceramics(white body) was extremely poor. (2) In the case of carbide, K01, the tool life in machining the white body was the longest, and the machinability of presintered ceramics becomes poorer with the increase of the presintering temperature. (3) The K01 tools exhibit longer life than the P10 tools in machining both the white body and the ceramics presintered at $1450^\circC$ or higher temperatures, but the P10 tools shows longer tool life than the K10 tools in machining of the ceramics presintered at temperatures below $1450^\circC$.