Equipment for printing of high viscosity liquids and molten metals

The common denominator of this thesis is the quest for processing a wider range of materials using inkjet technology, to allow for the realization of innovative manufacturing methods based on the precisely controlled placement in time and space of small portions of possibly different materials in order to build a complete product. One of the limiting factors in commercial available inkjet systems is the viscosity. To overcome this, a printhead has been developed, based on the very first inkjet principle developed, namely continuous inkjet. In this thesis the design phases of the complete print system are described. Several aspects are discussed all the way from the material supply mechanism, the droplet generation mechanism itself, towards means and methods to control the droplet landing position. To create a system which is as material independent as possible, deflection mechanisms are described requiring no material adaptation; droplet selection by collision, and droplet selection by air-jet. Thereafter several application areas are described, from powder generation towards novel encapsulation methods. For the realization of functional 3D electronics, using additive manufacturing techniques, it is required to create conductive tracks without additional high temperature processing steps. To that end two methods are described. The first process, pyrolitic metal printing, creates droplets of metal salt solutions which are pyrolised in flight on their way to the substrate. The second process, direct metal printing, deposits metal droplets directly from the melt. Therefore a printhead is developed capable of operating at 1140¿C allowing deposition of Feingold. Finally an overview is given of the challenges occurring when implementing the developed inkjet technology and creating a 3D layer-wise production system. Combining multiple materials into one single product opens new opportunities. The described process is used in one of the first systems capable of generating gradients in material properties within one product. Until now only nature was able to generate these structures. Now production technology is starting to catch up