Ultra high viscosity print head for 3D printing

November 25, 2021 // By Nick Flaherty
Ultra high viscosity print head for 3D printing
Xaar’s Ultra High Viscosity technology is providing new 3D production possibilities following the sale of its 3D printing joint venture to Stratasys

Xaar in Cambridge has developed print head technology for ultra high viscosity materials for 3D printing

Traditionally, industrial inkjet printing applications have had a recommended nominal jetting viscosity of up to 10-12cP affected by printhead architecture, flow rates, temperature and fluid handling capabilities. The development of Xaar’s TF Technology helped enable the transition of inkjet into the industrial ceramics market, where fluids loaded with more particles pushed the base viscosity higher.

However, it is only with the further development of new enabling technology and the latest printheads that this has changed more significantly. The stabilisation of increased particle concentrations and densities, and the ability to explore higher viscosities in applications such as 3D photopolymer jetting and beyond, have now become viable.

The capability to handle a much wider range of fluids at viscosities of up to 100 centipoises (cP), is increasing the relevance and practicability of inkjet technology across a variety of new printing, coating, advanced (functional fluids) and additive manufacturing applications. It is rapidly becoming the manufacturing technology for additive manufacturing and 3D printing, as well as for personalisation, coating and other innovative print and manufacturing processes.

This capability is increasing the relevance and practicability of inkjet technology across a variety of new printing, coating, advanced and additive manufacturing applications. It is rapidly becoming the manufacturing technology for Additive Manufacturing and 3D printing, as well as for personalisation, coating and other manufacturing processes.

“Ultra High Viscosity Technology offers a wide range of new 3D and Additive Manufacturing possibilities which are really as wide as the customer can think of,” said Mike Seal, Xaar’s Head of Advanced Applications, Technologies and Fluids.

Xaar is working with a number of fluid partners to establish the viscosity capability of its printheads, and this has shown so far that a standard 3-cycle greyscale mode can print a viscosity of 65cP at 70°C.

 While using high laydown mode, viscosities of up to 125cP can be jetted. Ongoing research is continuing to push these levels even further. In fact we have recently jetted 100cP fluids in our laboratory using our 2002 GS6 printhead in 3-cycle mode (equivalent to over 1000cP at 23°C). This enables even higher viscosities at high resolution (720dpi).

By combining the increase in base viscosity with an (albeit reduced) increase in jetting temperature there is a greater impact on the viscosity limit of materials at room temperature. As an example, taking the jetting of a photopolymer of 65cP at 70°C would actually be 1400cP at 20°C.

High viscosity fluids do however present some challenges on the ink system design, and in many ways need to be handled very differently to “standard” viscosity fluids. To achieve the same flow rate through the channels at higher viscosity, the differential pressure needs to be proportionally higher due to the increased flow resistance, however this means that any fluctuations in the pressure control system are also magnified.

“We’re giving people a new tool to create better products and with Ultra High Viscosity transforming 3D printing by enabling extra material properties that aren’t possible with other inkjet printheads. With inkjet technology the only difference between your final prototype and your product, is just the number you produce,” said Seal.

www.xaar.com

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