• 대한치과기공학회지
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• 제26권1호
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• pp.105-114
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• 2004

This study obtained the following consequences, as a result of the comparative analysis for the castability depending on an angle of the sprue and wax pattern in case of manufacturing dental prostheses, for the castability depending on direction, and for the castablility of sprue, which attached the reserve to each different 3.5mm roll wax(sprue wax) and to 2.5mm sprue wax. 1. As a result of the comparative analysis for the castability depending on an angle of the sprue and wax pattern, the best castability was shown when the angle of the sprue and wax pattern is 180$^{\circ}\Delta$(straight line), and the lowest castability was shown in 45$^{\circ}\Delta$, which was curved most, and there was no statistical significance. 2. As a result of the comparative analysis for the castability of an angle depending on direction, the best castability was shown in the farthest side from the direction of centrifugal casting, and the lowest castability was shown in the same side as the direction of centrifugal casting, and there was no statistical significance. 3. Given comparing the castability depending on the pattern of sprue, the better castability was shown in 135$^{\circ}\Delta$ and 180$^{\circ}\Delta$ when using 3.5mm roll wax(sprue wax), compared to attaching the reserve to 2.5mm sprue wax.

• 대한치과보철학회지
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• 제18권1호
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• pp.87-97
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• 1980

To compare the castability of various alloys popularly used in Korea for porcelain-fused-to-metal restorations, author selected Degudent G as precious alloy, J.P. 92 as semiprecious alloy and Vera Bond, Rexillium III, Unit Bond, Fine Bond as non precious alloys. With nylon lines and gauge waxes, author made the wax patterns for the castability comparison test. In the same conditions, wax patterns were invested, burned out and cast. Author obtained the following results from this study. 1. The castability of Degudent G as precious alloy for porcelain-fused-to-metal crown and bridge was the best of all. 2. The castability of nonprecious alloys was less than Degudent G as precious alloy, but their differences were not large. 3. The castability of Rexillium III is the best of all nonprecious alloys and that of Vera Bond, Unit Bond had nearly the same results. 4. Semiprecious alloy (J.P. 92) was less castable than nonprecious alloys.

• 대한치과보철학회지
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• 제45권4호
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• pp.522-533
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• 2007

Statement of problem: Despite of the recent development of the titanium casting system methods, the casting defects such as imperfect casting and internal porosity were frequently observed. Purpose: The purposes of this study were to compare and measure the castability, microhardness, and surface reaction between Grade 2 pure titanium and Ti-6Al-4V by casting these alloys from the different sprue design conditions. Material and methods: Depending on the sprue designs and titanium alloys, 42 ready-made wax patterns were used. By analyzing the remodeling of the cast, internal porosity, microhardness, and titanium surface layer of SEM, there were several results we observed. Results: 1. The measured castability of titanium were categorized in the ascending order: individual sprue group, runner bar group, and single group. This data are based on the statistically signigicant differences. 2. The castability of titanium has not showed the statistically significant differences among the alloys. However, CP-Ti groups were superior to Ti-6Al-4V groups by showing the noticeable castability. 3. The surface layers of the castings of all groups have showed $5{\mu}m$ titanium oxide layers irrespective of sprue designs and titanium alloys. Conclusion: From the above study results, by fabricating the restorations from the centrifugal casting machine direct sprue designs revealed better castability. As we increased the number of sprues in the wax pattern, it revealed better castability. The castability of pure titanium rather than that of Ti-6Al-4V was remarkable. To fabricate the complex forms of the restorations, further researches on the efficient sprue designs and titanium alloys must be made.

• 대한치과기공학회지
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• 제35권2호
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• pp.105-112
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• 2013

Purpose: This study was to analyze the castability, surface oxide characteristic of Co-Cr alloy for porcelain fused to metal crown and the bonding strength of porcelain fused to metal crown. Co-Cr and Ni-Cr alloy for porcelain fused to metal crown was used for tests of the castability and surface oxide state and shear bonding strength by various porcelain. The aim of this study was to suggest the differences of result according to Co-Cr and Ni-Cr alloy. Methods: The kinds of alloy as test specimen was Co-Cr and Ni-Cr alloy. The castability index on the alloy specimens. The surfaces of two alloys were analyzed by SEM and EDX in order to observe oxide characteristic. And the shear test was performed by MTS. Results: The castability index of Co-Cr alloy was 96.8% and Ni-Cr alloy was 94.4%. The strongest bonding strength of Co-Cr alloy was shown 67.37 MPa. Conclusion: The shear bonding strength between Co-Cr alloy and EX3 porcelain was the strongest comparing with others. And all of each alloy was indicated as same level about the castability.

• 대한치과기공학회지
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• 제9권1호
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• pp.21-29
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• 1987

The purpose of this investigation was to determine the effect of recasting on the castability and physical properties of the nonprecious metal alloy. Using 2 sorts of the nonprecious metal alloy for production of Crown and Bridge prosthetics, such as 1) sankin C. B 80 metal 2) C & B alloy, the result of experimental research on the castability and hardness according to the recasting, is as followes; 1. The difference of castability between sankin CB80 metal and C & B alloy was statistically significant (p < 0.01) and the difference of castability among the test groups, was statistically significant (p <0.01). 2. In the case of sankin C.B 80 metal, the difference of castability among the New alloy and first mixed alloy and second mixed alloy and old alloy was not significant statistically (p >0.05). 3. In the case of C & B alloy, the difference of castability among the New alloy and mixed alloys and old alloy, was not significant statistically (p >0.05). 4. The difference of hardness between sankin C & B alloy was not significant statistically (p >0.05), but the difference of hardness among the test groups was statistically significant (p <0.01). 5. In the case of Sankin C.B 80 metal, the difference of hardness among the new ally and mixed alloys and old alloy was not significant statistically (p >0.05). 6. In the case of C & B alloy, the difference of hardness between New alloy and mixed alloys was not significant statistically (p >0.05) but the difference of hardness among the old alloy and New alloy and mixed alloys was statistically significant (p <0.01).

• 대한치과기공학회지
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• 제28권1호
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• pp.9-17
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• 2006

The purpose of this study was to evaluate the titanium castability with a spin type casting machine(TiCast, Super R, Selec, Osaka. Japan). We tested phosphate bonded investment "Rematitan$^{(R)}$Plus(Dentaurum, Inc., Pforzheim, Germany)"of mesh grid pattern and plate pattern. Four different mold temperatures(room temperature, 200$^{\circ}C$, 400$^{\circ}C$ and 600$^{\circ}C$) were prepared for the present study. In mesh grid pattern with spruing of $\varphi$0.88㎜ dimeter, when the mold temperature increased, high percentage of castability was gained. Mold temperature showed a highly significant(p<0.05) correlation on the castability, In plate pattern, the higher the mold temperature during casting, the greater the adhesive phenomenon between Ti surface and the investment.

• 대한치과기공학회지
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• 제8권1호
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• pp.37-43
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• 1986

The purpose of this study is to evalute the effects of melting and casting procedures on the castability of some N-Cr and Ag-Pd alloys. One Ag-Pd alloy and two Ni-Cr alloys were chosen for study, and the first casting group of these alloys were used as the control, and with which the castability of the first recase group and the mixture group of the first recast and as much amount of the first casting alloy was compared. The results of this study were as follows: 1. The castability of the first recast alloys veried significantly depending upon the presence or abscence of the first casting alloy and the kind of alloys. 2. When the first recast alloy was mixed with as much amount of the first casting alloy, there was no significant difference in castabilityh between the first recast group and the first casting group. 3. When the first recast alloy was used alone, the castability veried significantly depending upon the kind of alloys, i.e., the castability of Rexillium III and Palliag M was decreased significantly when compared with that of the first casting groups, while that of C & B Alloy was not.

• 대한치과기공학회지
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• 제8권1호
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• pp.51-55
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• 1986

The castability of base metal alloys for dental casting in influenced by burn-out temperature and recent percentage. Burn-out temperatures for casting are set at 200$^{\circ}F$ interval from 1000$^{\circ}F$ to 1800$^{\circ}F$. According to recast metal percent in new cast alloy metal alloys are tested. The results are as followings: 1. In the new alloy(100%), the castability is the most. 2. The burn-out temperature in 1600$\sim$1800$^{\circ}F$, castability of 100% new alloy was more four times than of 50% new alloy plus 50% recast alloy. The using of 50% new alloy and 50% recast alloy, therefore, was unlike in castability. 3. The burn-out temperature in 1600$^{\circ}F$, castability of 100% new alloy was more than four times in soaking 20 minutes, but there was no any difference at 18700$^{\circ}F$. 4. It is investigated that the optimal burn-out temperature is 1600$^{\circ}F$ for the C & B alloy.

• 대한치과기공학회지
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• 제10권1호
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• pp.5-10
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• 1988

The purpose of this study was to evaluate the effect of spure designs and air vent on the relative castability of the nonprecious alloys, commonly used to make ceamometal restorations. Samples of total 30 were constructed and devided into 6 groups according to two variables, sprue design and air bent. The total number of completly cast squares was counted, verified, and recorded. The results obtained were as follows: 1. The runner bar or Rousseau designs yield better castability than reservoir design(P<0.1) 2. When the air vent was attached, only the castability of reservoir design was significantly different from runner bar or Rousseau designs.

• 대한치과기공학회지
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• 제29권1호
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• pp.133-138
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• 2007

In this study, the castability and of commercially pure titanium(c.p.Ti) grade according to the casting condition which are the vacuum condition in casting machine and mold temperature of investment, was investigated. Argon-arc melt/centrifugal casting machine was used for casting the specimens. The microstructure and mechanical properties were evaluated by using optical microscope. The results were as follows; 1. It could make a sure that there's relatively not much defect of casting body of c.p.Ti according to the deference of air pressure. 2. It could make sure that it formed porosity on the surface inside of the casting body of c.p.Ti according to deferent temperature. and on excellent castability was below $200^{\circ}C$ 3. As the mold temperature of investment was increased, the lamellar structure of phase and coarse grains were shown, especially under 42MPa.