Polish IT services company Zdalny Serwis is accelerating the development of its Duroplast Reactive Inkjet Printing (DRIP) 3D printing technology with the view of launching a complete printing system later this year.
The company is currently working on an FDM upgrade for its fully functional prototype DRIP printer to enable the printing of support structures for parts, and has been working to formulate a range of polyurethane-based materials with both rigid and elastic properties that are optimized for the upcoming DRIP system.
“We think that this technology has applications in printed organic electronics and biotechnology, as the printing of hydrogels with alginates is quite easy with this technology we are currently exploring an ink that allows cartilage printing, but it is in the early research phase,” said Maciej Zawadzki, Head of R&D at Zdalny Serwis.
“The mixing of different biocompatible inks with pharmaceuticals could allow for the production of drug delivery systems, and the ability to print functionally graded materials is further enhancing the possible applications, such as composite materials.”
DRIP 3D printing
Zawadzki and his team began developing their DRIP 3D printing technology in 2016 and obtained financing from the Polish National Center for R&D two years later to advance the process. Now, the team has a fully functional prototype DRIP 3D printing system and is continually working on new ink compositions to enhance print stability and improve material properties.
Defining DRIP, Zawadzki explained: “The whole concept lies somewhere between reactive additive manufacturing (RAM), PolyJet, and reactive inkjet printing.”
The technology involves colliding ink droplets in mid-air which react rapidly at the moment of contact in order to form 3D printed parts.
Achieving coalescence of the jetted droplets is important to ensure that the desired reaction between the different inks occurs reliably. To do this, a separator and inert gas atmosphere prevent the ink dispenser from clogging and guarantee stable operation of the printhead. Meanwhile, an integrated controller measures the droplets and recalculates the jetting parameters when necessary.
Once deposited, the combined droplets containing the reactive inks begin curing immediately after being mixed, forming a gel structure in a matter of seconds so the material doesn’t flow under its own weight. Full curing of the 3D printed object takes around 24 hours.
Inkjet based 3D printing presents researchers with opportunity of creating microscopic and complex devices for use in medical and chemical research, in addition to Microfluidics and lab on a chip device applications, due to its drop on demand precision.
In recent years, variations of the technology have been deployed for precise medical and chemical research, for applications of so-called 2.5D printing, and in the development of other novel hybrid additive manufacturing processes.
Achieving different properties through DRIP
According to the company, layer deposition time and reaction time between the inks are key parameters that influence variations in the properties of the printed objects. The DRIP prototype printer is reportedly capable of achieving combined droplet deposition precision of more than 10um with 300um diameter combined droplets.
As such, that the ink droplets can be reliably collided and coalesced with frequencies of up to 1kHz, with online automatic correction of dispensing times as well as droplet volumes and velocities. This control enables the DRIP printer to alter the mixing ratios of the reactive inks to allow for the production of functional grade materials.
Since the technology was first developed, the Zdalny Serwis team have expanded the printing system to include two printhead systems that facilitate the mixing of different types of materials in one print. The company is currently focused on the development of inks based on polyureas and polyurethanes but has also successfully tested silicones and acrylates.
DRIP enables the mixing of different components in different proportions in order to obtain materials with changing parameters. For instance, lowering the amount of the hardening agent during the printing process will result with materials with higher elasticity. As the company changes the proportions during the printing process, it can manufacture products with a gradual change of properties.
“We have developed a system that enables stable operation ensuring repeatable coalescence of the droplets with high droplet deposition accuracy,” said Zawadzki. “In our opinion, this technology is very promising but requires more special materials to fully showcase its advantages.”
Combining DRIP with FDM
With the DRIP printer slated to officially launch later this year, Zawadzki and his team have been working on an FDM upgrade for the machine to enable the printing of support structures and the intertwining of FDM materials with the reactive inks.
According to the company, the upgrade will become available sometime in the summer, in time for the printer’s unveiling in the autumn.
“In the future, it would be possible to create reactive special FDM filaments to obtain a reaction between different material layers,” said Zawadzki. “The materials we plan to launch with are based on polyurethanes with rigid or elastic properties that have better material properties than currently available TPU for FDM.”
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Featured image shows the prototype DRIP 3D printer. Photo via Zdalny Serwis.
