• Design & Manufacturing
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• v.8 no.1
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• pp.27-30
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• 2014

Alloy tool steel such as SKD11 and SKD61 or high speed tool like SKH51 are used as materials for semiconductor dies. Cavities, curl blocks, pot blocks and housings are made from those materials. To make those parts from alloy tool steel or high speed tool, one utilizes discharge machining, and mechanical machining including machining center, milling, drilling, forming grinding and others. In the process of cutting machining and polishing, the die materials become unsuitable for machining owing to bubbles and foreign substances in them, which hinders production process. Therefore, this study focuses on die material selection criteria, and on analysis and comparison of material characteristics to help companies to solve their problems, make die manufacture less burdensome and extend die life.

• Tribology and Lubricants
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• v.26 no.2
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• pp.105-110
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• 2010

In order to investigate the wear behavior of aluminum alloy depended on different hardness of the mating tool steel, sliding wear tests were conducted. It was found that the wear characteristics pattern of aluminum alloy for sliding speed was not affected by the hardness of the mating tool steel. However, the effects of the hardness of the mating tool steel exhibited only in relatively low sliding speed ranges. At these ranges, the wear rate of aluminum alloy decreased when increasing the hardness of the mating tool steel. This was attributed by the fact that $Al_2O_3$ particles released from the aluminum worn surface were crushed and embedded on the mating worn surface with high hardness level. At the high sliding speed ranges, wear of aluminum alloy was hardly occurred by the formation of thick $Al_2O_3$ film on the worn surface, regardless of the hardness of the mating tool steel.

• Tribology and Lubricants
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• v.19 no.3
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• pp.151-158
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• 2003

In metal cutting at the tool-chip interface, friction generates considerable amount of heat. Thus, the knowledge of wear properties of cutting tool material in high temperature has been as one of important factors in need of clarification. The authors presented the wear properties of 5%Co-5%V-1%Nb high speed steel, fabricated by powder metallurgy, in room temperature in previous articles. The objective of this paper is to clarify the effects of temperature on its wear properties. Wear tests in sliding conditions under various temperatures have been conducted using the pin-on-disc type wear test machine. The results indicate that the wear properties of 5%Co-5%V-1%Nb high speed steel in high temperature as well as in room temperature are excellent. It may be deduced that the oxide layer formed on worn surface at high temperature is stable enough to prevent wear due to the high temperature strength of its matrix.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.33-38
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• 1998

TiYN coated high speed steel tools have been developed and their tool lifes were assessed. First yttrium alloyed titanium target was manufactured, then using the arc ion plating(AIP) technique TiYN coating was deposited onto high speed steel substrate. Three kinds of varying thickness of TiYN coated tools were prepared. Cutting tests were carried out with theses tools and for comparison with the commercially available uncoated, TiN, TiCN and TiAlN coated tools. During the cutting tests flank wear width vs. cutting time was measured. It has been revealed that the newly developed TiYN coated tools show superior tool life characteristics to others.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.113-116
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• 2003

To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. During the high speed operation of moving frames or spindles, vibration problems are apt to occur if the machine tool structures are made of conventional steel materials with inferior damping characteristics. However, self-excited vibration or chatter is bound to occur during high speed machining when cutting speed exceeds the stability limit of machine tool. Chatter is undesirable because of its adverse effect on surface finish, machining accuracy, and tool lift. Furthermore, chatter is a major cause of reducing production rate because, if no remedy can be found, metal removal rates have to be lowered until vibration-free performances is obtained. Also, the resonant vibration of machine tools frequently occurs when operating frequency approaches one of their natural frequencies because machine tools have several natural frequencies due to their many continuous structural elements. However, these vibration problems are closely related to damping characteristics of machine tool structures. This paper presents the use of polymer concrete and sandwich structures to overcome vibration problems. The polymer concrete has high potential for machine tool bed due to its good damping characteristics with moderate stiffness. In this study, a polymer concrete bed combined with welded steel structure i.e., a hybrid structure was designed and manufactured for a high-speed gantry-type milling. Also. its dynamic characteristics were measured by modal tests.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.2
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• pp.41-46
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• 1984

The machinability of calicium-deoxidized steel is studied in turning by being compared with that of Fe-Si deoxidized steel under a given set of cutting condition. Tool life, cutting force and cutting mechanism are examined on a few sorts of steel. It is found that adhesive layer "Belag" is developed on the cemented carbide tool and the peak value is observed at the cutting speed of 300m/min followed by gradual increase in the thickness of Belag with the increase of cutting speed. the maximum thickness of Belag is also shown at the feed of 0.3mm/rev. On the other hand, the tool life of carbide tool is more favorable than that of high speed steel (SKH 9) in cutting calcium- deoxidized steel. It is considered that the steel deoxidized with Ca-Si shows better machinability a little than that with Fe-Si. However, the cutting force and the shear angle of the former are similar to those of the latter in turning.n turning.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.6
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• pp.112-119
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• 1995

Early fracture and cutting force of ceramic tool for hardened STC3 steel was investigated in this study. It was found that early fracture of ceramic tool was mostly occurred before normal wear was progressed beyond a critical cutting speed and normal wear was performed under the critical cutting speed. The relationships among critical cutting speed, which was a cause of early fracture, suggested cutting cross section, that is, maximum thickness of cut and width of cut, and cutting force were examined. The following conclusions were obtained: (1)Critical cutting speed showed a high value in the case of small maximum thickness of cut and large nose radius, but was not influenced by width of cut, (2)Principal, feed and radial force, respectively, showed the proportional value to constant cutting area, width of cut and maximum thickness of cut orderly, (3)Occurrence of early fracture was dependent upon radial force.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.458-461
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• 2016

In this study, a finite element analysis for high-speed blanking of mild steel is performed. A thermomechanically coupled simulation model of a blanking process was developed using ABAQUS/Explicit. Through a simulation of the high-speed blanking process of mild steel, the influence of the punch speed, tool edge radius, and work material thickness on the development of the plastic heat and punch load were studied. The results of the study revealed that a higher punch speed caused thermal softening of the work material and decreased the punch load. Decreasing tool edge radius could help reduce the punch load. In addition, the results of the study revealed that the thermal softening effect was more dominant in the blanking of a mild steel sheet with a greater thickness as compared to that in the blanking of a mild steel sheet with a lower thickness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.878-881
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• 2000

Recently high speed machining is being studied actively to reduce machining time and to improve machining precision. To perform efficient high speed machining, evaluation of high speed machinability must be studied preferentially and it can be identified by investigation of cutting force, tool wear and surface roughness. In this study. the cutting force and tool wear and surface roughness are investigated in case of various cutting conditions for hardened die steel.

• Archives of Metallurgy and Materials
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• v.64 no.2
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• pp.571-578
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• 2019

The densification behavior of H13 tool steel powder by dual speed laser scanning strategy have been characterized for selective laser melting process, one of powder bed fusion based metal 3d printing. Under limited given laser power, the laser re-melting increases the relative density and hardness of H13 tool steel with closing pores. The single melt-pool analysis shows that the pores are located on top area of melt pool when the scanning speed is over 400 mm/s while the low scanning speed of 200 mm/s generates pores beneath the melt pool in the form of keyhole mode with the high energy input from the laser. With the second laser scanning, the pores on top area of melt pools are efficiently closed with proper dual combination of scan speed. However pores located beneath the melt pools could not be removed by second laser scanning. When each layer of 3d printing are re-melted, the relative density and hardness are improved for most dual combination of scanning. Among the scan speed combination, the 600 mm/s by 400 mm/s leads to the highest relative density, 99.94 % with hardness of 53.5 HRC. This densification characterization with H13 tool steel laser re-melting can be efficiently applied for tool steel component manufacturing via metal 3d printing.