Watanabe I, Ohkubo C, Ford J P, Atsuta M, Okabe T
Department of Fixed Prosthodontics, Nagasaki University, School of Dentistry, Nagasaki, Japan.
Dent Mater. 2000 Nov;16(6):420-5. doi: 10.1016/s0109-5641(00)00038-5.
The purpose of this study was to investigate the cutting efficiency of air-turbine burs on cast free-machining titanium alloy (DT2F) and to compare the results with those for cast commercially pure (CP) Ti, Ti-6Al-4V alloy, and dental casting alloys.
The cast metal (DT2F, CP Ti, Ti-6Al-4V, Type IV gold alloy and Co-Cr alloy) specimens were cut with air-turbine burs (carbide burs and diamond points) at air pressures of 138 or 207 kPa and a cutting force of 0.784 N. The cutting efficiency of each bur was evaluated as volume loss calculated from the weight loss cut for 5 s and the density of each metal. The bulk microhardness was measured to correlate the machinability and the hardness of each metal.
The amounts of DT2F cut with the carbide burs were significantly (p < 0.05) greater than for the other titanium specimens at either 138 or 207 kPa. The diamond points exhibited similar machining efficiency among all metals except for Type IV gold alloy. The increase in the volume loss of Co-Cr alloy (Vitallium) cut with the diamond points showed a negative value (-29%) with an increase in air pressure from 138 to 207 kPa. There was a negative correlation between the amounts of metal removed (volume loss) and the hardness (r2 = 0.689) when the carbide burs were used.
The results of this study indicated that a free-machining titanium alloy (DT2F) exhibited better machinability compared to CP Ti and Ti-6Al-4V alloy when using carbide fissure burs. When machining cast CP Ti and its alloys, carbide fissure burs possessed a greater machining efficiency than the diamond points and are recommended for titanium dental prostheses.
本研究旨在调查气涡轮车针切割铸造易切削钛合金（DT2F）的效率，并将结果与铸造工业纯钛（CP Ti）、Ti-6Al-4V合金及牙科铸造合金的切割结果进行比较。
用气涡轮车针（硬质合金车针和金刚石磨头）在138或207 kPa的气压及0.784 N的切割力下切割铸造金属（DT2F、CP Ti、Ti-6Al-4V、IV型金合金和钴铬合金）试件。每根车针的切割效率通过根据5 s切割的重量损失及每种金属的密度计算出的体积损失来评估。测量整体显微硬度以关联每种金属的可加工性和硬度。
在138或207 kPa气压下，用硬质合金车针切割DT2F的量显著（p < 0.05）大于其他钛试件。除IV型金合金外，金刚石磨头在所有金属中表现出相似的加工效率。随着气压从138 kPa增加到207 kPa，用金刚石磨头切割钴铬合金（维他灵）的体积损失增加显示为负值（-29%）。使用硬质合金车针时，去除的金属量（体积损失）与硬度之间存在负相关（r2 = 0.689）。
本研究结果表明，在使用硬质合金裂钻时，易切削钛合金（DT2F）比CP Ti和Ti-6Al-4V合金表现出更好的可加工性。在加工铸造CP Ti及其合金时，硬质合金裂钻比金刚石磨头具有更高的加工效率，推荐用于钛制牙科修复体。
