Development of electric-discharge type metal jet nozzle for printer

Molten metals such as gold, silver and nickel are unable to be jetted through an ordinary nozzle, because it is very hard to melt metals with the high melting points in the small printer, extremely high heat-resistance in nozzle elements are required and high temperature exerts high internal stresses in the nozzle due to thermal expansion. Furthermore, high response of start and stop of printer can not be expected with an ordinary nozzle. The authors have invented a new nozzle which can shoot, with high response, a droplet of molten metal with a high melting point. In this nozzle, a tip of gold wire inserted through an injection pipe is melted by electric-discharge and a molten droplet at the tip of the wire is shot out of a pipe by a gas pulse jet. In this paper, a proto-type of a printer using this type of nozzle is developed and its performance such as droplet size, frequency and accuracy of shoots is shown.