| 3125 New Casting Method Using the Trial Production Assembly Ring | ||
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Z. ZHANG, Y. TAMAKI, Y. HOTTA, and T. MIYAZAKI, Showa University, Tokyo, Japan Objectives: To prevent environmental contamination from increasing, a new casting method using assembly ring was investigated. The purpose of this research was to decrease the quantity of the investment material by use of the secondary burying method. Methods: Commercial phosphate-bonded investment (Optivest, Degussa, Germany) and its special liquid were selected as a coating material. To check the fit of castings, tapered metal die was prepared and ring–shaped wax patterns were made. Trial assembly ring included four parts: bottom, crucible, ring and cover. Wax pattern was sprued on the crucible set on the bottom, the slurry of Optivest mixed using special liquid on the glass board with cement spatula was coated on the surface of wax pattern about 1mm thickness carefully, after set, the ring was assembled and trial sand (average particle size 275μm, it could be reused for many time as it was) without kneading was filled into the ring, the cover was screwed last. Casting ring was heated up to 850°C at a speed of 10°C/min, held for 30min, commercial gold alloy (Ishifuku, Japan) was cast by a centrifugal casting apparatus (Yoshida, Japan). As control, castings were also fabricated using Optivest according to manufacture's instruction. Castability and dimensional change of the castings (n=5) were evaluated between new casting method and ordinary usage. Results: Casting defects were never observed obtained with the new casting method, but the dimensional change was different with that of control. Compared with the wax pattern, the average gap value of castings obtained from new method was 30.30μm, and obviously smaller than that of control. There were significantly differences between them by One-way ANOVA (p<0.05). Conclusion: The experimental new casting method with assembly ring was possible to cast dental alloy although some problems on dimensional change were still remained. | ||
| Seq #338 - Special Topics 2:00 PM-4:00 PM, Saturday, 12 March 2005 Baltimore Convention Center Exhibit Hall E-F | ||
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