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0.05). The standard deviation of the distance of 6 to 6 in the water/powder ratio of 33∶10 was extraordinary big(s=0.206).②The time of pouring generated dimensional shrink(P
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Objective:To study the technical operation of self-developed investment (FUS-invest) for titanium crown and bridge. Methods:Orthogonal design was done. Four factors were taken into account, i.e. water/powder ratio, adhesive/hardener ratio, fine powder proportion in refractory and agitation time. And each factor was ranked into three levels. Slurry fluidity, initial setting time and setting time of every experiment group were studied. Grain size graduation of the best group was measured.Results:Fluidity, initial setting time and setting time were most greatly affected by water/powder ratio and secondly by fine powder proportion in refractory. When water/powder ratio was 7.5∶1 and the content of fine powder was 35%, slurry fluidity was better and initial setting time and setting time were appropriate. When the content of fine powder of AFS fineness number 300 was 31.31%, fineness number 100 was (40.09%), fineness number 70 was 18.05% and adhesive/hardness ratio was 200∶1, the perfect titanium castings could be fabricated. Conclution:The best rules of technical operation for perfect titanium castings are water/powder ratio (7.5)∶1, the content of fine powder 35% and adhesive/hardener ratio 200∶1.