Development of a Semiautomatic Machine for the Drop On Demand Three Dimensional Printing

A Three Dimensional Printing (3DP) machine system integrating a Drop on Demand (DoD) printhead is presented. It is based on the rapid prototyping technology developed since the last decade at MIT. To build a three-dimensional part, powder beds are manually spread and powder grains are selectively bound by liquid drops from an inkjet style printhead. Successive layers are added until the part is completed. The machine target use is making small-scale tests with the real working parameters for the development of new material systems and it is specifically designed to print and examine single scanlines. Hardware design includes two axes working space and a PC-based control system. Special software to control the printhead and the main axes in different configurations, to print rings and lines, with continuously changing parameters has been developed, which generates a detailed report for the process monitoring. Methods for the printhead characterization are also described, including a new fast technique to estimate the drop speed. The machine has been successfully exploited using different binders (water solutions of colloidal silica in ethylene glycol and poly acrilic acid) and powders (ceramics and metals). An overview of the available inkjet printing technologies is also given in the paper.