Direct Metal Rapid Casting: mechanical optimization and tolerance evaluation.

The ZCast Direct Metal Casting process allows the direct fabrication of ceramic moulds and cores through Three Dimensional Printing. It ensures low costs and extremely short times for the production of cast metal prototypes, but the knowledge on the expected performances is still lacking. This paper describes a set of experiments done on Z-cast components, in order to evaluate the mechanical and dimensional performances and their dependence on the production parameters.Cylindrical samples have been manufactured and subjected to different posttreatments, varying process time and temperature. The baked parts, as well as some green ones for comparison, have undergone compression tests and the rupture surfaces have been observed using S.E.M.. The results proved that time has anegligible effect on the compressive strength, whereas temperature can be optimized for parts’ best mechanical response. For the evaluation of the dimensional performances, a specific benchmark has been designed, built and treated following the thermal cycle previously identified. Uniformly distributed measurements have been made on the benchmark before and after baking using a CMM. In the last part the paper evaluates the tolerance values and calculates the correct IT class location for the considered process.