• Title/Summary/Keyword: Poor machinability

Search Result 37, Processing Time 0.035 seconds

Machinability Evaluation of CBN Ball End Milling in Die & Mold Steels with High Hardness (고경도 금형강의 CBN 볼 엔드밀 가공에서 가공성 평가)

  • Kim, Hong-Gyoo;Sim, Jae-Hyung;Lee, Jong-Chan
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.16 no.4
    • /
    • pp.119-126
    • /
    • 2007
  • Generally, the machinability of materials that have a good mechanical properties is poor. The material having a high strength, high toughness in high temperature and wear resistance, it is difficult to remove a chip from workpiece. STD11 and NAK80 are kinds of these materials and these materials can be used in many industrial fields. But it is limited in use because of high cost and poor machinability. In this experimental study, the cutting of STD11 and NAK80 were used to decide the machinability and the tool shape of CBN ball end mill. From the results, the CBN ball end mill is verified that the estimated cutting edge shape of rake angle 30 degree has consistent effect on the tool wear and cutting force.

A Study on Tapping for STS304 and Tap Geometry (STS304의 태핑과 탭 형상에 관한 연구)

  • Lee, Jung-Kil;Choi, Man-Sung
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.17 no.11
    • /
    • pp.55-62
    • /
    • 2000
  • The poor machinability material such as austenite stainless steel(STS304) is emphasized on the wide use of HSSE for the tapping operation. The difficulty can be entirely to tapping torque due to chip formation through the hole of tap. The object of this study is to investigate tap geometry affecting the tapping torque from a practical point of view. The study shows that the optima tapping torque is affected by the tap geometry and cutting condition for STS304.

  • PDF

Tool Wear in Turning of the Presintered Low Purity Alumina (저순도 알루미나 예비소결체 선삭시의 공구 마멸)

  • Lee Jae-Woo
    • 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 $1450^\circC$.

PRODUCTION AND MACHINABILITY OF SiCp-REINFORCED AL-2014 ALLOY MATRIX COMPOSITES

  • Ciftci, I.;Sahin, Y.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • 2002.10b
    • /
    • pp.313-314
    • /
    • 2002
  • SiCp-reinforced metal matrix composites (MMCs) containing 8 wt % and 16 wt % of $SiC_p-reinforced$ with 30 and $45\;{\mu}m$ in sizes were prepared by a melt stirring-squeeze casting technique. Microstructural observation showed that particle distributions were reasonably well. Turning experiments were carried out on the composites using uncoated and triple-layer coated carbide tools at various cutting speeds under a constant feed rate and depth of cut. Coated tools indicated better performance than uncoated tools for all the materials while the poor surface finish was obtained for coated tools.

  • PDF

저순도 알루미나 세라믹 가소결재의 피삭성

  • 이재우
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1995.04b
    • /
    • pp.33-38
    • /
    • 1995
  • In this study, unsistered, pre-sintered and sintered low purity alumina ceramics were machined with various tools to clarify the machniability, the optimum tool materials and the optimum tool materials and the optimum cutting conditions. The maon conclusions obtained were as follows. (1) Machined withalloy steel tool, the machinabilty of te pre-sintered ceramics becomes better with the decrease of pre-sintering temperature, but that of unsintered ceramics(white body) was extremely poor. (2) In the case of carbide tool K01, the tool life in machining white body was the longest, and the machinabilty of pre-sintered ceramics becomes poorer with the increase of the pre-sintering temperature. (3) In the case of ceramic tool, the 10000-1100 .deg. C pre-sintered ceramics showed te best machinability within a certain cutting speed range. So far as dry machining, the above combination and conditions showed the highest productivity. (4) When the pre-sintered ceramics were wet machined withsintered diamond tool, the tool life becomes extremelylong, and higher cutting speed can be can be used than in the case offull-sintered ceramics. The productivity of wet cutting is much higher than that ofdry cutting.

  • PDF

A Study on Machinability Evaluation of Inconel 718 in Flat End Milling (Inconel 718의 평엔드밀링가공에서 가공성평가에 관한 연구)

  • Jeong, Jihoon;Kwon, Haewoong;Koo, Joonyoung;Kim, Pyeongho;Kim, Jeongsuk
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.21 no.6
    • /
    • pp.982-987
    • /
    • 2012
  • Inconel 718 alloy has been widely used in the aerospace, heavy industry and electronic industry. However, the machinability of this alloy is very poor, which is attributed to their inherent high strength that is maintained at elevated temperatures. The tool life is dominant problem in machining difficult-to-cut materials, so it is necessary to select the efficient cutting conditions for the improvement of tool life. In this study, the cutting force, tool wear and surface roughness are investigated in end milling machining under various cutting conditions. By this experiment, the efficient machining condition of this alloy is suggested to adopt in various industries.

Effect of NbC Carbide Addition on Mechanical Properties of Matrix-Type Cold-Work Tool Steel (매트릭스(matrix)형 냉간금형강의 기계적 특성에 미치는 NbC 탄화물 첨가의 영향)

  • Kang, Jun-Yun;Kim, Hoyoung;Son, Dongmin;Lee, Jae-Jin;Yun, Hyo Yun;Lee, Tae-Ho;Park, Seong-Jun;Park, Soon Keun
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.28 no.5
    • /
    • pp.239-249
    • /
    • 2015
  • Various amount of NbC carbide was intentionally formed in a matrix-type cold-work tool steel by controlled amount of Nb and C addition. And the effect of NbC addition on the mechanical properties was investigated. Four alloys with different Nb and C contents were cast by vacuum induction melting, then hot forging and spheroidizing annealing were conducted. The machinability of the annealed specimens was examined with 3 different cutting tools. And tensile tests at room temperature were conducted. After quenching and tempering, hardness and impact toughness were measured, while wear resistance was evaluated by disk-on-plate type wear test. The increasing amount of NbC addition resulted in degraded machinability with increased strength, whereas the absence of NbC also led to poor machinability due to high toughness. After quenching and tempering, the additional NbC improved wear resistance with increasing hardness, whereas it deteriorated impact toughness. Therefore, it could be found that a moderate addition of NbC was desirable for the balanced combination of mechanical properties.

Effect of Nickel Content on Corrosion Resistance and Machinability of Fe-23Cr-2.5C-1.2Si-1.08Mn-0.48Mo-0.3V-xNi Cast Iron (Fe-23Cr-2.5C-1.2Si-1.08Mn-0.48Mo-0.3V-xNi 주철의 내식성 및 피삭성에 미치는 Ni의 영향)

  • Kim, Ki-Bin;Jung, Sung-Sik;Baek, Min-Sook;Yoon, Dong Joo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.3
    • /
    • pp.576-584
    • /
    • 2020
  • The extruder screw material is mainly SKD11, but the recent development of synthetic resins have increased the occurrence of chemical corrosion and wear. To solve this issue, high chromium cast iron is needed because of its good abrasion resistance and corrosion resistance, but its use is avoided because of its poor machinability. In this study, to improve the machinability of high chrome cast iron, 0, 0.5, 1.0, 1.5% of nickel, which has excellent workability, was added to high chromium cast iron with a composition of Fe-23Cr-2.5C-1.2Si-1.08Mn-0.48Mo-0.3V, and annealed after casting. Subsequently, the effect of nickel on the machinability and corrosion resistance was analyzed using a turning test and coin polarization test, and compared with SKD11. After casting using a high-frequency vacuum induction furnace, the annealing treatment was performed at 750 ℃ for five hours and then reheated at 1100 ℃ for five hours. A turning test after annealing at 750 ℃ showed that the machinability was improved remarkably when the nickel content was over 1.0%. In the potentiodynamic polarization test in a 5% NaCl solution, the corrosion resistance decreased with increasing nickel content in the as-cast and annealing treatment. On the other hand, after reheating, the corrosion resistance was best with a 1.5% nickel content.

Nano-turning of single crystal silicon (단결정 실리콘의 초정밀가공)

  • 김건희;도철진;홍권희;유병주;원종호;박상진;안병민
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2000.11a
    • /
    • pp.939-942
    • /
    • 2000
  • Single point diamond turning technique for optical crystals is reported in this paper. The main factors influencing the machined surface quality are discovered and regularities of machining process are drawn. Optical crystals have found more and more important applications in the field of modern optics. Optical crystals are mostly brittle materials of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency, poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimum machining conditions for ductile cutting of optical crystals and apply the SPDT technique to the manufacturing of ultra precision optical components of brittle material.

  • PDF

The Characteristics of Ultra Precision Machining of Optical Crystal (광학소자의 초정밀절삭 특성에 관한 연구)

  • 김주환;박원규;김건희;원종호
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2003.06a
    • /
    • pp.529-532
    • /
    • 2003
  • Machining technique for optical crystals with single point diamond turning tool is reported in this paper. The main factors influencing the machined surface quality are discovered and regularities of machining process are drawn. Optical crystals have found more and more important applications in the field of modern optics. Optical crystals are mostly brittle materials of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency. poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimum machining conditions for ductile cutting of optical crystals and apply the SPDT technique to the manufacturing of ultra precision optical components of brittle materials. As a result. the surface roughness is good when spindle speed is 200m/min. and teed rate is small. The influence of depth of cut is very small.

  • PDF