Evaluation of cast metallic posts reproduction according to its quantity and position inside the casting ring

Abstract

The aim of this study was the evaluation about the influence of the quantity and the localization of resin patterns to cast metallic posts in its diameter and length reproduction. Seventy-two patterns for posts were fabricated by using prefabricated FKG plastic posts and divided for casting in 3 groups: G1-small ring/4 patterns, G2- medium ring/6 patterns, G3- big ring/8 patterns. Half of the patterns of each group were placed on the right side of the ring midline and the other half, on the left side, in order to guide the ring inside of the centrifuge. Using the comparative microscope, measures of diameter and length in different places were obtained before and after casting. The results were submitted to statistic analysis (ANOVA two way and Tukey's test), to make possible these observations: 1°) the position of patterns didn't influenced the measured dimensions. 2°) the same happened with the quantity of patterns inside the ring. 3°) only the pins of group G3 have presented statistically significant diameter differences. In conclusion, 1°) the position of patterns inside the ring and its quantity did not result in significant changes in pins length and diameter. 2°) Although there were no significant length alterations, significant ones were observed in the diameters 3, 6, and 9mm of Group G3.

Influence of investment granulometry on the castability and surface roughness of castings obtained with Ni/Cr alloys

“…As regards granulometry, however, they differ: Heat Shock ® presents rougher particles, whereas Castotal ® has finer particles. The finer the particles of an investment, the smaller will be the surface irregularities of a casting 29,[32][33][34][35] . Therefore, it was not possible to completely accept the tested hypothesis.…”