• Title/Summary/Keyword: Mold steels

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Evaluation of thermal characteristics by cutting environments in high speed ball end-milling (볼엔드밀을 이용한 고속가공에서 가공환경 변화에 따른 열특성 평가)

  • 이채문
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.34-38
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    • 2000
  • The trend of cutting process today goes toward higher precision and higher efficiency. Many thermal/frictional troubles occur in high-speed machining of die and mold steels.In this paper, the thermal characteristics are evaluated in high sped ball end-milling of hardened steel(HRc42). Experimental work is performed on the effect of cutting environments on tool life and cutting temperature. Cutting environments involve dry, wet(20bar), compressed chilly air at -9$^{\circ}C$, compressed chilly air at -35$^{\circ}C$. The measuring technique of cutting temperature using implanted thermocouple is used. The cutting temperature is about 79$0^{\circ}C$, 35$0^{\circ}C$ and 54$0^{\circ}C$ in dry, wet and compressed chilly air at +9$^{\circ}C$, respectively. The tool life for compressed chilly air at -9$^{\circ}C$ is longer than all other cutting environments in experiment.

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Correlation between Microstructure and Mechanical Properties of the Additive Manufactured H13 Tool Steel (적층 제조된 H13 공구강의 미세조직과 기계적 특성간의 상관관계)

  • An, Woojin;Park, Junhyeok;Lee, Jungsub;Choe, Jungho;Jung, Im Doo;Yu, Ji-Hun;Kim, Sangshik;Sung, Hyokyung
    • Korean Journal of Materials Research
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    • v.28 no.11
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    • pp.663-670
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    • 2018
  • H13 tool steels are widely used as metallic mold materials due to their high hardness and thermal stability. Recently, many studies are undertaken to satisfy the demands for manufacturing the complex shape of the mold using a 3D printing technique. It is reported that the mechanical properties of 3D printed materials are lower than those of commercial forged alloys owing to micropores. In this study, we investigate the effect of microstructures and defects on mechanical properties in the 3D printed H13 tool steels. H13 tool steel is fabricated using a selective laser melting(SLM) process with a scan speed of 200 mm/s and a layer thickness of $25{\mu}m$. Microstructures are observed and porosities are measured by optical and scanning electron microscopy in the X-, Y-, and Z-directions with various the build heights. Tiny keyhole type pores are observed with a porosity of 0.4 %, which shows the lowest porosity in the center region. The measured Vickers hardness is around 550 HV and the yield and tensile strength are 1400 and 1700 MPa, respectively. The tensile properties are predicted using two empirical equations through the measured values of the Vickers hardness. The prediction of tensile strength has high accuracy with the experimental data of the 3D printed H13 tool steel. The effects of porosities and unmelted powders on mechanical properties are also elucidated by the metallic fractography analysis to understand tensile and fracture behavior.

Corrosion and Oxidation Behaviors of ion-nitrided tool Steels (이온질화된 공구강 표면의 산화 및 공식거동)

  • Choe Han-Cheol;Lee Ho-Jong;Jeong Yong-Woon
    • Journal of the Korean institute of surface engineering
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    • v.38 no.3
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    • pp.126-135
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    • 2005
  • SKD 11 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness and creep strength as well as excellent oxidation resistance. The ion nitrided tool steel containing Mo results in improvement of corrosion resistance, strength at high temperature and pitting resistance, especially in $Cl^-$ contained environment. But the Mo addition causes a disadvantage such as lower oxidation resistance at elevated temperature. In this study, several effects of ion-disadvantage on the oxidation characteristics for SKD 11 steel with various oxidation temperature were investigated. SKD 11 steels were manufactured by using vacuum furnace and solutionized for 1 hr at $1,050^{\circ}C$. Steel surface was ion nitrided at $500^{\circ}C$ for 1 hr and 5 hr by ion nitriding equipment. ion nitrided specimen were investigated by SEM, OM and hardness tester. Oxidation was carried out by using muffle furnace in air at $500^{\circ}C,\;700^{\circ}C\;and\;900^{\circ}C$ for 1hr, respectively. Oxidation behavior of the ion nitrided specimen was investigated by SEM, EDX and surface roughness tester. The conclusions of this study are as follows: It was found that plasma nitriding for 5 hr at $500^{\circ}C$, compared with ion nitriding for 1 hr at $500^{\circ}C$, had a thick nitrided layer and produced a layer with good wear, corrosion resistance and hardness as nitriding time increased. Nitrided SKD 11 alloy for 1hr showed that wear resistance and hardness decreased, whereas surface roughness increased, compared with nitrided SKD 11 alloy for 5 hr. The oxidation surface at $900^{\circ}C$ showed a good corrosion resistance.

Characteristics of Heat Generation in time of High-speed Machining using Infrared Thermal Imaging Camera (적외선 열화상 카메라를 이용한 고속가공에서의 열 발생 특성)

  • Lee, Sang-Jin;Park, Won-Kyu;Lee, Sang-Tae;Lee, Woo-Young;Ha, Man-Kyung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.2 no.3
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    • pp.26-33
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    • 2003
  • The term 'High Speed Machining' has been used for many years to describe end milling with small diameter tools at high rotational speeds, typically 10,000-100,000rpm. The process was applied in the aerospace industry for the machining of light alloys, notably aluminum. In recent year, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. With increasing cutting speed used in modern machining operation, the thermal aspects of cutting become more and mole Important. It not only directly influences in rate of tool weal, but also affects machining precision recognized as thermal expansion and the roughness of the surface finish. Hence, one needs to accurately evaluate the rate of cutting heat generation and temperature distributions on the machining surface. To overcome the heat generation, we used to cutting fluid. Cutting fluid plays a roles in metal cutting process. Mechanically coupled effectiveness of cutting fluids affect to friction coefficient at tool-workpiece interface and cutting temperature and chip control, surface finish, tool wear and form accuracy. Through this study, we examined the behavior of heat generation in high-speed machining and the cooling performance of various cooling methods.

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Temperature Measurement when High-speed Machining using Infra-red Thermal Imaging Camera (적외선 열화상 카메라를 이용한 고속가공에서의 열 발생 특성)

  • 김흥배;이우영;최성주;유중학
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.422-428
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    • 2001
  • The term High Speed Machining has been used for many years to describe end milling with small diameter tools at high rotational speeds, typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry for the machining of light alloys, notably aluminium. In recent year, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. With increasing cutting speed used in modern machining operation, the thermal aspects of cutting become more and more important. It not only directly influences in rate of tool wear, but also will affect machining precision recognized as thermal expansion and the roughness of the surface finish. Hence, one needs to accurately evaluate the rate of cutting heat generation and temperature distributions on the machining surface. To overcome the heat generation, we used to cutting fluid. Cutting fluid play a roles in metal cutting process. Mechanically coupled effectiveness of cutting fluids affect to friction coefficient at tool-work-piece interface and cutting temperature and chip control, surface finish, tool wear and form accuracy. Through this study, we examined the behavior of heat generation in high-speed machining and the cooling performance of various cooling methods.

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The Characteristics of High-Speed Machining of Aluminum Wall Using End-Mill (엔드밀을 이용한 알루미늄 측벽 형상의 고속가공 특성)

  • 이우영;최성주;김흥배;손일복
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.912-916
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    • 2000
  • The term ‘High Speed Machining’has been used for many years to describe end milling with small diameter tools at high rotational speeds, typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry fur the machining of light alloys, notably aluminium. In recent you, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. And the end mill is an important tool in the milling process. A typical examples for the end mill is the milling of pocket and slot in which a lot of material is removed from the workpiece. Therefore the proper selection of cutting parameter fur end milling is one of the important factors affecting the cutting cost. The one of the advantages of HSM is cutting thin-walled part of light alloy like Al(thinkness about 0.1mm). In this paper, firstly, we study characteristics of HSM, and then, we choose the optimal parameters(cutting forces) to cut thin-walled Al part by experiment.

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A Study on the High-Speed Machining of Thin-wall Part (고속가공에서 박막 측벽(Thin wall) 파트 가공을 위한 연구)

  • 김흥배;이우영;최성주
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.10a
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    • pp.343-348
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    • 2000
  • The term‘High Speed Machining’has been used for many years to describe end milling with small diameter tools at high rotational speeds. typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry for the machining of light alloys, notably aluminium. In recent years, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. And the end-mill is an important tool in the milling process. A typical examples for the end mill is the milling of pocket and slot in which a lot of material is removed from the workpiece. Therefore the proper selection of cutting parameters for end milling is one of the important factors affecting the cutting cost. The one of the advantages of HSM is cutting thin-wall part of light alloy like Al (thinkness about 0.3mm). In this paper, firstly, we study characteristics of HSM, and then, we choose the optimal parameters(cutting forces) and investigate various machining strategies to cut thin-wall part by experiment.

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Development of High Functional Black Resin Coated Electrogalvanized Steel Sheet for Digital TV Panel

  • Jo, Du-Hwan;Kwon, Moonjae;Lee, Jae-Hwa;Kang, Hee-Seung;Jung, Yong-Gyun;Song, Yon-Kyun;Jung, Min-Hwan;Cho, Soo-Hyoun;Cho, Yeong-Bong;Cho, Myoung-Rae;Cho, Byoung-Chon;Lim, Kwangsoo;Seon, Pan-Woo;Han, Hyeon-Soop;Jeong, Hwon-Woo;Lee, Jae-Ryung;Kim, Jong-Sang
    • Corrosion Science and Technology
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    • v.12 no.1
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    • pp.1-6
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    • 2013
  • Recently Digital TV industry has drastically been moving the illuminating system, which causes an obvious product change from PDP and LCD to LED model to provide high-definition image. Due to strong competition in the digital industry, TV manufacturers make a great efforts to reduce production cost by using low-priced materials such as steels instead of aluminum and plastic etc. In this paper we have developed a new low-priced electrogalvanized steel sheet, which has a black resin composite layer, to substitute conventional high-priced PCM steel and plastic mold for rear cover panel in the digital TV. The black resin composite was prepared by mechanical dispersion of the mixture solution that consists of high solid polyester resin, melamine hardener, black pigment, micronized silica paste, polyacrylate texturing particle and miscellaneous additives. The composite solution was coated on the steel sheet using roll coater followed by induction furnace curing and cooling. Although the coated layer has a half thickness compared to the conventional PCM steels having $23{\mu}m$ thickness, it exhibits excellent quality for the usage of rear cover panel. The new steel sheet was applied to test products to get quality certification from worldwide electronic appliance customers. Detailed discussion provides in this paper including preparation of composite solution, roll coating technology, induction curing technology and quality evaluation from customers.

Effects of the Solid Solution Heat Treatment on the Corrosion Resistance Property of SSC13 Cast Alloy (SSC13 주강품의 내부식특성에 미치는 고용화 열처리 영향)

  • Kim, Kuk-Jin;Lim, Su-Gun;Pak, S.J.
    • Corrosion Science and Technology
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    • v.14 no.2
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    • pp.93-98
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    • 2015
  • Recently, Stainless steels have been increasingly selected as the fitting or the valve materials of water pipes as the human health issue is getting higher and higher. Therefore, the connectors attached at pipes to deliver water are exposed to more severe environments than the pipes because crevice or galvanic corrosion is apt to occur at the fittings or the valves. Effects of the solid solution annealing, cooling rate after this heat treatment, and passivation on the corrosion properties of the shell mold casted SSC13 (STS304 alloy equivalent) were studied. The heating and quenching treatment more or less reduced hardness but effectively improved corrosion resistance. It was explained by the reduction of delta ferrite contents. Independent of heat treatment, the chemical passivation treatment also lowered corrosion rate but the improvement of corrosion resistance depended on temperature and time for passivation treatment indicating that the optimum conditions for passivation treatment were the bath temperature of $34^{\circ}C$ and operating time of 10 minutes. Therefore it is suggested that the corrosion resistance of SSC13 can be effectively improved with the heat treatment, where SSC13 is heated for 10 minutes at $1120^{\circ}C$ and quenched and passivation treatment, where SSC13 is passivated for at least 10 seconds at $34^{\circ}C$ nitric acid solution.

Mechanical Properties and Formability of TWB Boron Steel (TWB 보론강의 기계적 특성 및 성형성)

  • Nam, K.W.;Hwang, S.H.;Kim, D.Y.;Lee, M.Y.;Lee, S.M.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.10
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    • pp.1221-1226
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    • 2012
  • The hot-stamping technique is a forming method used for manufacturing high-strength parts, in which a part is cooled rapidly after press forming above the austenite transformation temperature. Boron steel, which contains a very small amount of boron, is one of the materials used for hot stamping. The purpose of this study is to investigate the mechanical properties of boron steel according to the heat-treatment conditions and the formability by using an Erichsen cupping test. Die quenching from various temperatures was conducted for different elapsed heat-treatment times. Laser-welded boron steel after quenching at 1173 K-0 s has a tensile strength of 1203 MPa. This is 79% of the tensile strength of the base metal (1522 MPa). The formability of boron steel was not significantly different from that at the mold temperature. However, it decreased with increasing forming speed. These properties provide practical information for the use of boron steels for hot stamping.