Three Dimensional Printing: Rapid Tooling and Prototypes Directly from a CAD Model

Three Dimensional Printing is a process for the manufacture of tooling and functional prototype parts directly from computer models. Three Dimensional Printing functions by the deposition of powdered material in layers and the selective binding of the powder by “ink-jet” printing of a binder material. Following the sequential application of layers, the unbound power is removed, resulting in a complex three-dimensional part. The process may be applied to the production of metal, ceramic, and metal-ceramic composite parts. An experiment employing continuous-jet ink-jet printing technology has produced a three-dimensional ceramic part constructed of 50 layers, each 0.005 in. thick. The powder is alumina and the binder is colloidal silica. The minimum feature size is 0.017 in., and features intended to be 0.5000 in. apart average 0.4997 in. apart in the green state and 0.5012 in. apart in the cured state, with standard deviations of 0.0005 in. and 0.0018 in., respectively. Future research will be directed toward the direct fabrication of cores and shells for metal casting, and toward the fabrication of porous ceramic preforms for metal-ceramic composite parts.