• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.90-96
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• 2021

As real-time data of factories can be collected using various sensors, the adaptation of intelligent unmanned processing systems is spreading via the establishment of smart factories. In intelligent unmanned processing systems, data are collected in real time using sensors. The equipment is controlled by predicting future situations using the collected data. Particularly, a technology for the prediction of tool wear and for determining the exact timing of tool replacement is needed to prevent defected or unprocessed products due to tool breakage or tool wear. Directly measuring the tool wear in real time is difficult during the cutting process in milling. Therefore, tool wear should be predicted indirectly by analyzing the cutting load of the main spindle, current, vibration, noise, etc. In this study, data from the current and acceleration sensors; displacement data along the X, Y, and Z axes; tool wear value, and shape change data observed using Newroview were collected from the high-speed, two-edge, flat-end mill machining process of SKD11 steel. The support vector machine technique (machine learning technique) was applied to predict the amount of tool wear using the aforementioned data. Additionally, the prediction accuracies of all kernels were compared.

• Journal of Korea Foundry Society
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• v.42 no.3
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• pp.191-197
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• 2022

This study aims to improve the machinability of gray cast irons in high speed cutting by using nonmetallic inclusions. In this research, small quantities of AL and Mg were added to conventional gray cast irons without influencing their mechanical characteristics and castability to investigate the effects of these nonmetallic inclusions in the gray cast irons on tool wear in high speed cutting. During the high speed turning of gray cast iron containing Al and Mg using a cermet tool, protective layers consisting of Al, Mg, Si, Mn, S and O were detected on the flank face and rake face of the tool, and flank and crater wear were significantly reduced compared to the turning of conventional gray cast iron and gray cast iron added with Al. The effect of inclusions on tool wear increased with increasing cutting speed, and flank and crater wear was the smallest at the cutting speed of 700m/min. Moreover, in face milling, the addition of Al and Mg drastically decreased the wear rate, and wear hardly progressed even in prolonged cutting length after initial wear. The amount of adhesion on tool faces increased as the cutting speed increased. This increase in cutting speed resulted in the formation of a thick protective layer and the reduction of tool wear. Furthermore, the addition of small amounts of Al and Mg prevented thermal cracks in the face milling of gray cast irons.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.14-19
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• 1999

In order to evaluate the effect of Nb on wear properties of high speed steel by powder metallurgy(PM-HSS), niobium-alloyed PM-HSS have been prepared by adding 0%, 1%, 3% and 5%Nb to PM-HSS of 6%W-5%Mo-4%Cr-5%V-5%Co presented in the previous paper. Sliding wear test have been conducted in various sliding speed conditions under the constant pressure using a pin-on-disc type machine. The results of this study shows that the wear resistance of PM-HSS has been increased by the addition of Nb in the range of experimental sliding speed. However, the amount of Nb shows to be unimportant parameter for the improvement of the wear resistance. It may be due to the thermal stability of carbide and high temperature properties of matrix by adding Nb comparing to the case of no addition.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.94-100
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• 2000

This paper presents a methodology for In-Process monitoring of tool wear by using ultrasonic sensor in turning operation. An integrated single ultrasonic transducer operation at a frequency of 10MHz is placed in contact with the insert tip. The change in amount of the reflected energy from the nose and flank of the tool can be related to the level of tool wear and the mechanical integrity of the tool. As the results, the tool wear monitoring system based on the ultrasonic pulse-echo method was proposed, it is useful to determine a tool life and tool change time.

• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.71-78
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• 1991

Microstructure and characteristics of the SiCp/Al-4.5wt%Cu-1wt%Mg composites fabricated by the combination of the compocasting and the pressurized continuous casting process, which is one of the processes to decrease the limitations of the size, and shops of the products, are investigated. The main results are as follows: 1) the SiCp/Al alloy matrix composites can be made continuously 2) as the amount of SiCp addition increases; (1) the degree of directional solidification of matrix structure decreases, and that of SiCp dispersion improves, (2) wear resistance improves, and especially these composites show the excellent wear resistance under the high sliding speed and high final load condition, (3) wear mechanism of these composites is changed from adhesive wear into abrasive wear, and the tendency of that becomes outstanding with increasing sliding speed.

• Journal of Korea Foundry Society
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• v.22 no.4
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• pp.184-191
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• 2002

This study aims to investigate on the effects of alloying elements and heat treatment on the microstructures, wear and heat resistance of Al-Si-Cu-Mg-(Ni)/SiCp prepared by the duplex process developed in previous study, which consists of squeeze infiltration (1st process) and squeeze casting (2nd process). The hardness of composite increased with decrease in SiCp size and Ni addition in both the heat exposured composite and the as-cast one. And the heat and wear resisting properties was improved by the SiCp reinforcement and the Ni addition. The wear amount of Al/SiCp composite decreased with decreasing in the size of silicon carbide particle.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.479-487
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• 2007

Die life is generally estimated taking failure life and wear amount into consideration. In this study, the forging die life was investigated considering both of these two factors. The fatigue life prediction for the die was performed using the stress-life method, i.e. Goodman's and Gerber's equations. The Archard's wear model was used in the wear life simulation. These die life prediction techniques were applied to the die used in the forging process of the socket ball joint of a transportation system. A rigid-plastic finite element analysis for the die forging process of the socket ball was carried out and also the elastic stress analysis for the die set was performed in order to get basic data for the die fatigue life prediction. The wear volume of the die was measured using a 3-dimensional measurement apparatus. The simulation results were relatively in good agreement with the experimental measurements.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1176-1180
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• 1994

The sliding wear behavior of the plasma-sprayed zirconia containing 3 mol% yttria was investigated after the annealing at room temperature to 80$0^{\circ}C$ in various concentrations of humid atmosphere as laboratory, humid, dry argon atmosphere. Both of the friction coefficient and the wear loss increased with increasing temperature up to 80$0^{\circ}C$. Surface morphology of the worn samples changed with annealing temperature. The change of monoclinic/tetragonal (m/t) x-ray peak intensity ratio effected the wear behavior. The m/t ratio had maximum value at 20$0^{\circ}C$ and decreased with increased temperature in laboratory and humid atmosphere. In argon atmosphere the m/t ratio had no maximum value and decreased with increasing temperature. At all the annealing temperature humid atmosphere had more the m/t ratio value than any other atmosphere. The change of toughness was showed the inversed result of m/t ratio change. The results indicated that the resudial stress which was induced by the different amount of phase transformation takes a detrimental role in wear behavior.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.5
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• pp.380-385
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• 2016

Railway tracks are repeatedly overstressed and damaged owing to increase in passing tonnage and numerous contact cycles between wheels of train and rails. In order to ensure safe train operation, heat-treated rails are used in addition to regular inspection and maintenance of these rails. Normal rails were treated using ultrasonic nanocrystal surface modification (UNSM) to strengthen the surface of rails. A few changes in surface properties were detected with respect to hardness and compressive residual stress after UNSM treatment. Wear and rolling contact fatigue tests were performed using rails whose surfaces were hardened by UNSM and heat-treated rails. The amount of wear and fatigue life cycles were measured to estimate the effect of UNSM on the rail material. The material of the surfacehardened rail showed improved wear and rolling contact fatigue properties.

• Tribology and Lubricants
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• v.15 no.4
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• pp.314-320
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• 1999

Friction and wear characteristics of phenolic resin-based friction materials reinforced with aramid pulp and potassium titanate were investigated using a pad-on-disk type friction tester. Friction characteristics such as friction stability, thermal stability, and wear rate varied according to the type of phenolic resins and the relative amount of aramid pulp and potassium titanate. The modified novolac resin-based friction materials showed better heat resistance and friction stability than those with the unmodified(straight) novolac resin. Compared with friction materials filled with potassium titanate or aramid pulp only, the friction materials reinforced with both aramid pulp and potassium titanate showed good friction stability and wear resistance. Increment of aramid pulp from 10 to 20 vol.% however, showed little difference in friction stability.