• Title/Summary/Keyword: Metal casting

Search Result 593, Processing Time 0.022 seconds

Investigation of Gas Evolution in Shell Cores during Casting Processes of Aluminum Alloys (알루미늄 합금 주조공정의 쉘 코아 가스 발생 전산모사 연구)

  • In-Sung Cho;Jeong-Ho Nam;Hee-Soo Kim
    • Journal of Korea Foundry Society
    • /
    • v.43 no.4
    • /
    • pp.187-193
    • /
    • 2023
  • Shell core making is an excellent process in terms of formability and desanding, but when the molten aluminum comes into con- tact with the shell core, gas generation by pyrolysis of the resin is inevitable. In addition, when the ventilation is inadequate, pores will remain inside the casting, which can directly lead to defects of the casting. While studies on the gas generation behavior of shell core making have been reported, the modeling of gas generation has not been extensively investigated. We will develop a gas evolution analysis method that considers the relationship between temperature and gas quantity for the core to be developed. We then use the developed method to analyze the flow and solidification behavior of metal molten metal during core mold design and low-pressure casting of cylinder head products, and predict the occurrence of casting defects to derive a casting method that min- imizes the occurrence of defects.

A STUDY ON THE DISTORTION OF THE COPINGS FOR CERAMOMETAL CROWNS DURING REPEATED FIRING (도재전장금관을 위한 코핑의 변형에 관한 연구)

  • Lee, Ki-Hong;Chung, Hun-Young;Lee, Sun-Hyung;Yang, Jae-Ho
    • The Journal of Korean Academy of Prosthodontics
    • /
    • v.35 no.4
    • /
    • pp.706-718
    • /
    • 1997
  • Ceramometal crowns are common restorations in fixed prosthodontics because of their casting accuracy, the high strength properties of the metal, and the cosmetic appearance of porcelain. However, deterioration of the initial fit of the metal coping has been observed after the porcelain firing cycle. The distortion due to repeated firing makes it difficult to fit crown margin and elicits microleakage. The major causes of distortion are the residual stress that accumulate during wax-up, casting, cold work and the induced stress caused by the mismatch of porcelain-metal thermal contraction. This study examined the marginal fit changes of metal copings in relation to repeated firing and the effects of heat treatment that reduce the distortion resulted from residual stress. The marginal changes of the copings that were treated with conventional method and those treated with heat before repeated firing, were evaluated. The metal die which represented preparations of a maxillary central incisor was fabricated, and 45 wax patterns were cast with nonprecious metal alloys. The heat treatment of each group was performed as follows. Group 1(control) : Casting - Devesting - Cold work - Firing Group 2 : Casting - Heat treatment - Devesting - Cold work - Firing Group 3 : Casting - Devesting - Cold work - Reinvesting - Heat treatment - Devesting - Firing The copings were fired 3 times. After each firing, the marginal fit changes were measured with inverted metallurgical microscope at the 4 reference points located at labial, lingual, and both proximal surface. Measurements were compared, and statistically analyzed. The results were as follows ; 1. In all groups, the highest value of marginal fit changes of the copings studied were found after the first firing cycle. 2. When the distortion of each experimental group at the first firing cycle were compared, group 1 exhibited the greatest changes($20-27{\mu}m$), followed by group 2($9-13{\mu}m$), and group 3($8-10{\mu}m$). 3. The copings treated with heat before devesting(group 2) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 4. The copings treated with heat after reinvesting(group 3) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 5. No siginificant differences in marginal fit changes were found between the copings treated with heat before devesting(group 2) and the copings treated with heat after reinvesting(group 3). (p>0.01)

  • PDF

A Study on the Acoustic Properties of Acoustic Treansducer with PZT/Metal (PZT/Metal로 구성된 음향변환기의 음향특성에 관한 연구)

  • Kim, Jin-Soo;Kang, Dae-Ha;Kim, So-Jung;Kim, Ho-Gi;Lee, Deok-Chool
    • The Journal of the Acoustical Society of Korea
    • /
    • v.11 no.2
    • /
    • pp.28-37
    • /
    • 1992
  • In the study, the Acoustic transducer of a thin circular disc-type with PZT/Metal was manufactured. The 'tape casting method' was introduced to prepare the thin disc-type of piezoelectric ceramics. The acoustic characteristics of PZT/Metal acoustic transducer for piezoelectric buzzer and piezoelectric speaker etc. have been studied and analyzed. As a result, the sound pressure level (dB), in the range from -6dB to -14dB, increased with increasing the piezoelectric coeffeicient ($d_{31}$) of ceramics. The optimal conditions of the sound pressure characteristics of acoustic transducer were that the radius ratio(${\eta}$) of ceramics and metal plate is 0.7-0.8 and the thickness ratio(${\beta}$) is 1.0, and the value were -15~-165dB.

  • PDF

A Study on the Frictional Abrasion Properties of MMC (금속기 복합재료의 마찰ㆍ마모 특성에 관한 연구)

  • 이광영;박원조;허선철
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.10 no.6
    • /
    • pp.171-177
    • /
    • 2002
  • Metal matrix composites had generated a lot of interest in recent times because of significant in specific properties, it was also highlighted as the material of frontier industry because strength, heat-resistant, corrosion-resistant and wear-resistant were superiored. In recent years, the study of metal matrix composite has increased by aluminum alloy. The study is based on the tribological properties of AC4CH that is a part of the mechanical property of metal matrix composites. Metal matrix composite that is produced from matrix material AC4CH and reinforcement SiO$_2$, Al$_2$O$_3$ and TiO$_2$ are added to the metal matrix composite fur strength so binding among the whisker can take place. Each metal matrix composite is produced using the squeeze casting method. To test for tribe a pin-on-disk machine and lubricant is used without paraffine 8.2CST at room temperature which is 40$\^{C}$. As the results of this study, the tribological properties of each specimen are more improved than AC4CH. The variation of coefficient resistance is more stable at the AC4CH and TiO$_2$, but the variation rates are higher at the inanimate binder.

A study on the computed aided gating design in gray cast iron (컴퓨터를 이용한 회주철의 탕구방안 설계에 관한 연구)

  • Choi, Jeong-Kil;Kim, Dong-Ok
    • Journal of Korea Foundry Society
    • /
    • v.6 no.1
    • /
    • pp.27-35
    • /
    • 1986
  • The gating design of gray cast iron was programmed in a Personal computer. By this program, casting test was done. The results obtained are as follows. 1. Gating design that can calculate the velocity of metal flow and size in each gate section by knowing the loss coefficient caused by friction loss and bend loss was programmed. 2. In the test casting, the gating ratio was changed into 1.1:1.3:1, 1:2:2, 1:4:4. And sound casting, free of sand washing defect, was obtained at the velocity of 35.5cm/sec in ingate.

  • PDF

A Study on Terminology of Metal Handles in Traditional Korean Furniture - Focusing on Korean and Western Furniture - (한국전통가구의 금속 손잡이 영문표기 연구 - 한국 및 서구를 중심으로 -)

  • Moon, Sun-Ok
    • Journal of the Korea Furniture Society
    • /
    • v.23 no.4
    • /
    • pp.449-459
    • /
    • 2012
  • The article aims to making a comparison between traditional Korean and Western furniture metal handles to give the detail information of the handle terms by analyzing the related literature including internet and interviews. In terms of that, the Korean and Western metal handles are compared in the types, components, materials, methods, and terms affecting the development made by the craftsmen before the Industrial Revolution about the mid or late 18th century. As a result, first, ring and drop pull handles were mostly and wooden knobs were a little used to open the furniture doors and drawers. The Korean drop pulls, Deulswae, came out after the ring pulls, Gori, while the Western drops called loop or bail handles as well, came out before the ring pulls. Second, the components were composed by ring, Gori, loop or bail, Deulswae, Post, Baemok, washer, Baemokbatchim, and backplate, Deulswaebatchim. Most of the Western handles were fastened by the bolt and nut, while the post of two strips, Baemok, fastened the Korean metal handles. Third, the metal handles were created of brass and iron mostly, gilded gold and silver. Forth, the method were largely used by casting, engraving, forging, plating, and hammering in the Korean handles, and by casting, molding, engraving, and stamped in the Western handles. Finally, the terms such as "knobs, pulls, drops, ring and drop pulls, loop or bail handles, posts, washers, backplate, casting, molding, engraving, forging, plating, and stamped" were clarified by the two comparison in Korean and English.

  • PDF

Ceramic Direct Rapid Tooling with FDM 3D Printing Technology (FDM 3D Printing 기술을 응용한 직접식 세라믹 쾌속툴링)

  • Shin, Geun-Sik;Kweon, Hyun-Kyu;Kang, Yong-Goo;Oh, Won-Taek
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.18 no.7
    • /
    • pp.83-89
    • /
    • 2019
  • In the conventional casting and forging method, there is a disadvantage that a mold is an essential addition, and a production cost is increased when a small quantity is produced. In order to overcome this disadvantage, a metal 3D printing production method capable of directly forming a shape without a mold frame is mainly used. In particular, overseas research has been conducted on various materials, one of which is a metal printer. Similarly, domestic companies are also concentrating on the metal printer market. However, In this case of the conventional metal 3D printing method, it is difficult to meet the needs of the industry because of the high cost of materials, equipment and maintenance for product strength and production. To compensate for these weaknesses, printers have been developed that can be manufactured using sand mold, but they are not accessible to the printer company and are expensive to machine. Therefore, it is necessary to supply three-dimensional casting printers capable of metal molding by producing molds instead of conventional metal 3D printing methods. In this study, we intend to reduce the unit price by replacing the printing method used in the sand casting printer with the FDM method. In addition, Ag paste is used to design the output conditions and enable ceramic printing.

Composition of nickel-chromium alloy on the centrifugal casting and the influence of quantitative of oxides on the casting temperature (원심 주조한 니켈-크롬 합금의 성량 변화 및 주조 온도에 따른 산화물 측정)

  • Kim, Won-Soo
    • Journal of Technologic Dentistry
    • /
    • v.34 no.4
    • /
    • pp.361-368
    • /
    • 2012
  • Purpose: The aim of this study was to analysis the composition on the centrifugal casting and the oxide on the casting temperature. Methods: The nickel based alloy were used in this study. Wax pattern specimens (10*10*2) were invested with phosphate-bonded investment in metal rings, the liquid/powder ratio and overall burn-out schedules for these investments were followed in accordance with the manufacturer's instructions. After casting, the alloy specimens were evaluated as regards composition(EPMA). The casting temperatures were as follows: $1400^{\circ}C$ and $1700^{\circ}C$. The quantitative analysis of oxides were scanning electron microscope(SEM), energy dispersive spectroscopy(EDS) and line scanning. Results: Nearer the injection lines showed that there is a large amount of nickel. Quantitative of oxides of Ni-Cr alloy cast from $1400^{\circ}C$ is lager than Ni-Cr alloy cast from $1700^{\circ}C$. Conclusion: Casting when using a centrifugal casting machine centrifugal force affects the composition of the alloy. The higher the temperature, the amount of oxide that is generated many.

Evaluation of Metal-mold Reactions and Fluidity of TiAl Alloys (TiAl 합금의 주형계면반응 및 유동성 평가)

  • Lee, Sang-Hwa;Sung, Si-Young;Choi, Bong-Jae;Kim, Myoung-Gyun;Kim, Young-Jig
    • Journal of Korea Foundry Society
    • /
    • v.26 no.2
    • /
    • pp.98-103
    • /
    • 2006
  • Metal-mold reactions between investment mold and TiAl alloys were investigated for the economic net-shape forming of TiAl alloys. The effect of mold preheating temperatures on the metal-mold reaction were investigated using a vacuum induction-melting furnace. In the case of TiAl alloys, there were no ${\alpha}$-case formation reactions. There were neither interstitial nor substitutional ${\alpha}$-case formations as TiAl alloys have both negligible solubility of oxygen and low activity in molten states. The fluidity of TiAl alloys increases with mold preheating temperature since they have a peritectic reaction that appears in the form of envelope, surrounding each particles of the primary constituent. The results of the investment casting of TiAl alloys confirm that the casting route in our study can be an effective approach for the economic net-shape forming of TiAl alloys.