Effect of sprue design on the castability and internal porosity in pure titanium castings.

OBJECTIVE

The aim of the study was to evaluate the pure titanium castability and internal porosity with 3 different sprue designs.

METHOD AND MATERIALS

The sprue designs selected were the conventional cylindrical, funnel-shaped, and sheet-form sprue formers. To evaluate the castability, the mesh monitor was chosen. Eight mesh patterns (14 3 14 mm) of 49 squares were attached to each type of sprue design. They were invested in titanium investment material and cast in a semiautomatic titanium casting machine. The titanium castings were evaluated by 2 methods. One was the visual observation of the castings for completeness, and the second was the radiographic qualitative analysis for the location of the internal porosities.

RESULTS

Data were analyzed with analysis of variance and Student t test for paired comparison among different sprue designs. According to analysis of variance, all sprue designs revealed a statistically significant difference at the 5% level of confidence (P <.05, F = 3.50). Mesh patterns attached to funnel-shaped sprue designs showed better percentage castability values.

CONCLUSION

For titanium, casting using a funnel-shaped sprue design displayed better castability values and less internal porosities in the castings.