Introducing UV Inkjet 3D Printing by ChemStream
Personalized 3D printed ophthalmic lens. Printed by Luxexcel with ChemStream optical ink.
In this article, Marin Steenackers from Chemstream explains more about their new UV Inkjet 3D Printing technology which could well be a breakthrough technology, particularly with precision applications.
What is unique about UV Inkjet 3D Printing?
During the last decades, different 3D printing technologies have been developed such as Fused Deposition Modeling (FDM), Laser Sintering (LS), Stereolithografie (SLA) for the manufacturing of prototypes (Rapid Prototyping) as well as finished products (Digital Additive Manufacturing). Objects are usually printed with one single material leading to objects with one single set of material properties. A relatively young and strongly innovative branch within the 3D printing technology is UV Inkjet 3D Printing. Due to its unique combination of features, such as high resolution and the possibility of realizing multi-material objects, this technology has huge growth potential with a focus on Digital Additive Manufacturing. Furthermore, Inkjet 3D Printing is a highly productive Digital Additive Manufacturing technology which makes it applicable for industrial mass production.
By combining different printheads in one single print job, complex objects composed of several interwoven materials having each a different mechanical (hardness, elasticity, etc.), optical (color, opacity, refractive index, fluorescent, etc.), electrical (band gap, conductivity, etc.), chemical (hydrophilic/hydrophobic, etc.) and biological activity can be manufactured. This allows the production of objects with unprecedented and unique properties for applications in various fields such as optics, automotive and bio-medical devices (micro-reactors and lab-on-a-chip).
How is ChemStream involved in this type of inkjet printing?
ChemStream is mainly focusing on applications for which 3D inkjet printing is a unique production process, such as the digital manufacturing of Gradient-index (GRIN) optics or biocompatible multi material micro-reactors. Due to the high resolution of the Inkjet 3D Printing process, it is today the only 3D printing technology which allows the production of objects for optical applications with optically smooth surfaces without the need of (usually complex and expensive) post-processing steps such as varnishing and polishing.
In close communication with its customers, ChemStream designs as well the inkjet ink formulations as the necessary printing strategies in order to obtain the required properties of the printed objects.
How does it work?
UV Inkjet 3D printing uses UV-curable inks which are jetted with high precision as small droplets on the substrate (drop-on-demand). The printer consists of one or more printheads, an optional leveler and a UV curing station. After being jetted, the drops can optionally be flattened by a leveler before being cured. Then, the print table lowers down one layer thickness before the subsequent ink layer is printed. In analogy to conventional graphical 2D inkjet printing in which a color image is obtained by jetting simultaneously different colors, inks having different material properties can be printed simultaneously.
A modular 3D inkjet printing unit from VDW-Consulting bv allows ChemStream to develop and test its inks for 3D inkjet printing applications
Support ink
In order to print complex geometries, a support ink is required that can be removed after the print job. Different support inks for inkjet 3D printing are commercially available. Most support inks are phase change inks in which a solid wax is jetted above its melting temperature or UV curable inks that can be hydrolyzed after curing in an alkaline bath. In both options, it is practically impossible to create very narrow channels since the support ink cannot be removed easily or in very harsh conditions that may equally deteriorate the object material. Therefore, ChemStream has developed a water-soluble UV-curable inkjet ink which can be removed rapidly in plain tap water. This support ink technology in combination with advanced printing strategies form the basis for the manufacturing of micro-fluidic channels which are mandatory for high-end bioreactors, microreactors and microfluidic mixers.
Images above represent 3D printed microfluidic channels for high end bioreactors, microreactors and microfluidic mixers
What brings the future?
The translation of continuously new material requirements into industrially applicable 3D inkjet inks is a fascinating multidisciplinary research field. The realization of new challenges is not only feasible by the design and synthesis of new molecular ingredients and advanced formulation technology, but also by developing new printing strategies and digital manufacturing processes. Due to the unique combination of features, UV inkjet 3D Printing opens up a broad new variety of possibilities for the material science and digital manufacturing of tomorrow.
Contact Marin Steenackers for more information.