Use of DOE for 3D Printer Ink Formulation Development

presented by Uri Zadok

Stratasys is the world’s leading company in the field of 3D printing for over 30 years. It is one of the only companies producing printers capable of simultaneously printing in 7 colours, enabling also colour-mixing on the tray.

Stratasys’ PolyJet technology is similar to 2D inkjet printing in that it jets a thin layer of resin materials onto the surface, which is then polymerized on the surface using UV light. The process is then repeated multiple times, each layer adding thickness to the model. Using this method layers of 14-28 micrometers are printed giving high accuracy.

As in most formulated products, inkjet ink is a complex mixture, with many elements often having a contradictory effect. The inks must match the substrate, the hardware, and each other. This difficult endeavor is exacerbated in the case of 3D printing. Any small mismatch, defect, or problem will be enhanced as each layer is deposited on top of the previous one.

When jetting ink for 3D printing, a support material must be also printed beneath model material overhangs. This material must be strong enough to support the weight of the model above it, but also be easily removable after printing. In addition, due to the printing sequence and the internal environment inside the printer, the support material must have a certain resilience and thermal stability, and provide adequate surface quality of the model post support removal.

One major drawback of our printing technology is that it is virtually impossible to anticipate the performance of the ink in the lab, and we therefore have to print each and every formulation. This process is both lengthy and cumbersome.

The first incentive to use DOE for this particular product was that no matter what changes were made to the formulation, the polymerized support material would melt as the ambient temperature increased during the printing process. The second incentive was to arrive at a lead formulation with a minimal number of trials.

June 16 at 8:00am Central Time