Additive Manufacturing (3D-printing) has evolved into a versatile industrial production technology. In it, multi-material printing, including metals, is emerging rapidly. Inkjet specialist Océ – a Canon company – has developed a so-called ‘drop-on-demand’ printhead which can ‘jet’ various types of metal drops at temperatures of up to 1,800 degrees Celsius. Possible applications range from metal tracks on flexible electronics and ultra-thin connectors for chips, to microstructures on machine parts.
A 3D pioneer is the Additive Manufacturing and 3D Printing research group at the University of Nottingham in England. This group was the first to sign-up for a multi-metal printer based on the Océ technology, to carry out application research. Océ delivered the printheads and Demcon was commissioned to design a metal-jetting system in which these printheads would be integrated. The first multi-metal printer Demcon developed has four printheads and has now been delivered to the British researchers.
The metal-jetting system certainly posed a number of mechatronic challenges for Demcon. In this 3D printer, the printheads are static. That’s because of the required ‘infrastructure’ to keep the metals at a high temperature in their reservoirs. The platform on which the object can be printed moves under the heads. The trick is to provide the printing pulse at just the right moment for the next metal droplet to be deposited on the object which has already been printed on the moving platform. Metal droplets are formed by propelling molten metal to the exterior through a small opening in the printhead (nozzle). The propelling power is delivered by an electromagnetic force (the Lorentz principle).
As usual in 3D printing, jetting occurs in layers. A variety of metals can be printed in each layer, derived from different printheads. The ‘overlay’ between printed droplets from different heads within one layer is accurate to 5 micrometres, as is the overlay from layer to layer. The jet process is adjusted using an ImageXpert droplet analysis system, a high-speed camera with which the speed, diameter and camber angle of the metal droplets can be measured. Printing can be interrupted to check the jet process using this system.
In the design and realisation of the metal-jetting system, Demcon was able to integrate its mechatronics expertise with Océ’s inkjet technology. Thanks to this result, researchers can perform groundbreaking application research.