Abstract
This study is to evaluate the titanium castability with an all-directional pressure type casting machine, using two kind of phosphate bonded investments which have different gas permeabilityies. The pure titanium used was JIS grade 2. A mesh grid type pattern was used to measure the castability. An all-directional pressure type casting machine (AUTOCAST-HC III: GC Co.) was employed in this study. Two types of phosphate bonded investment were tested. The two materials were invested, heated and cast according to the manufacturer's instructions. Casting was performed with the mold at room temperature in both cases. Seven different sizes of mold diameter 25, 30, 35, 40, 45, 50, 55, 60mm were prepared for T-INVEST, and five 25, 35, 45, 55, 65 mm for T-INVEST C & B, respectively. Distance from the bottom to the pattern of the mold was 10, 20, 30 mm on each investment. It was concluded that a high percentage of castability (over 90%) was gained, when the mold diameter was increased with T-INVEST. Mold diameter at T-INVEST showed a significant (p<0.01) correlation to the castability. Furthermore, with T-INVEST C & B, high castability (over 90%) was shown under every condition. The change in distance change from pattern to bottom of the mold was not effective. This result seemed to be caused by non uniform contact between the bottom of the mold to the casting table. These results indicate that high performance of castability on titanium was achieved when gas permeability was decreased using an all-directional pressure type casting machine.
