Xaar launches Nitrox printhead
Xaar has introduced a new printhead, the Nitrox, a direct replacement to the 1003 that was first announced back in 2016, and which is capable of print speeds up to 100mpm at 720dpi resolution.
The Nitrox has the same Hybrid Side Shooter architecture and the same physical size as the 1003, with the same print width of 70mm and with 1000 nozzles at 360dpi. However, the major advantage of the Nitrox is that Xaar has upgraded the electronics as Michael Walsh, Xaar’s chief product architect, explains: “We have increased the data rate off the image and increased the frequency of the image getting sent to the printhead. In addition to that we have been able to upgrade how we generate wave forms and have come up with a new waveform development process that allows us to access these higher frequencies and as such we have moved from 36khz up to 48khz with this product.”
There’s a new Head Personality Card, HPC6, that’s needed to access the higher frequencies. Walsh adds: “And you will need a waveform so there would be a new waveform that goes along with the printhead, the ink and the HPC. Obviously we have a pack available for OEMs and third parties with the electronics and we can give them guidance on how to access these higher frequencies and that pack is available for anybody that wants to use the Nitrox.”
There are three variants, starting with the Nitrox Core, which is suitable for oil-based inks, such as those used in ceramic tile decoration. Then there’s the Pro version, which can handle more demanding fluids including soluble salts and frit used for printing glass as well as solvents. The top-of-the-range Elite version works with all these fluids as well as UV-curable fluids for coating and for decoration, including 3D applications as well as display graphics and label printing solutions.
All three of these can produce 6, 12 and 40pl drop sizes though the firing frequencies, and therefore the printing speed, varies: 36kHz for the Core and Elite versions for the smaller drop sizes; 48kHz for the Elite for the 6 and 12pl drops; and 24kHz for all versions for the 40pl drops. It’s worth noting that the most accurate dot placement seems to come from the Elite version, running 6pl drops at 48 kHz.
Walsh explains: “One of the key areas is accessing the 48khz and that allows us to do a couple of other things. One is we can either give for single pass a much higher line speed, so if you use a 48khz waveform and print at 720 dpi in a linear direction you can achieve up to 100mpm which was one of the key goals for web printing.
“The second one was to have a printhead that was capable of printing and scanning, such as for wide format graphics, and allowing machines to run at up to 1.7m/sec in the scanning direction. So, the applications we were after were predominantly graphics, looking to get that 100mpm for single pass labels, and then for the wide format graphics, getting the carriage speed up to 1.7m/sec.”
Xaar’s Nitrox printhead can print a 70mm with at 100mpm at 720dpi resolution.
Alignment and uniformity
The new Nitrox also benefits from recent Xaar features around alignment and uniformity, which makes it much easier to integrate and to replace in the field. This includes Tuned Actuator Manufacturing, which produces more uniformity between nozzles. The Nitrox also features AcuChp, which allows for better colour uniformity across each individual head as well as between groups of heads.
Walsh adds: “We have done really well with the 2002, with masses of positive feedback about the drop-in, plug-and-print capability so we wanted to lever off that and have brought out exactly the same features in the Xaar Nitrox so tightened up all the datum to first nozzle, first to last nozzle, the rotational alignment off the inkjet, everything that’s in the mechanical structure so it’s now drop-in capable and then you’ve got the AcuChp for the uniform colour tone along with the tuned actuator so that’s the TAM feature.”
It’s worth noting that the Nitrox could be used as a drop-in replacement for the 1003 in existing printers, complete with the advantage of the improved uniformity even without the electronic upgrades needed to use the faster speeds of the Nitrox.
High viscosity fluids
Naturally the Nitrox makes use of Xaar’s Through Flow TF recirculation, which ensures a constant flow of fluids directly past the back of the printhead nozzles, with a high flow rate to prevent sedimentation and nozzle blockages for greater reliability. This is used in combination with another unique Xaar technology, High Laydown, which can deposit large quantities of fluid in a single pass, useful for things such as a high build varnish or tactile effect.
These two technologies allow the use of very high viscosity fluids, as Walsh explains: “The Xaar architecture and the Through Flow enables us to go quite high in viscosity. With shared wall* we can go up to about 60 centipoise, and using high laydown we can push that up to 100cp. Normal is about 10-12cp so we can go from 10cp all the way through. Most things are graded according to the market, so for graphics you are looking at about 12cp, ceramics 18cp, and for moving into 3D you have much higher viscous fluids which are around about 40-50cp and then we can handle that entire range up to 60cp with shared wall and then high laydown gives us that extra boost up to 100cp.”
This has direct implications in the applications that these printheads can handle as Graham Tweedale, general manager of Xaar’s printhead business, explains: “We are seeing that the ability to go up to those very high viscosities really changes the chemistry that people can think about when they are developing fluids and inks. So, in advanced manufacturing, in 3D in particular, it allows you to develop fluids that have less monomers and more complex molecules within the fluid, so you get better cross linking of materials, and you get much stronger parts in advanced applications in particular for 3D printing. In more traditional graphic inks, because you can load much more pigment into the ink, which increases the viscosity, you can really increase the color gamut, and you can also really increase the opacity with white in single pass, so it just widens out the options for ink chemistry that we can support.”
He adds: “We have seen that people are really interested in being able to do things like white in a single pass and not having to do multi pass, because if you trade the two off, maybe the ink will cost more, but with a single pass there are some advantages there.”
Tweedale continues: “We have a number of 3D printer companies and materials manufacturers that are looking at how this capability widens the spectrum of materials that can be used and enables different applications in 3D. Because one of the real challenges is not just being able to print the shape and getting it dimensionally correct, it’s having the right mechanical properties and chemical resistance which is a real challenge, so that’s an area where we see we have quite a lot of advantages because you can just have that wider set of options for the chemistry of the fluid.”
Working with higher viscosity fluids also presents challenges to the ink system used to deliver the fluid to the printheads. Walsh explains: We have two ink systems that are available to us, the Hydra and the Midas. The Hydra is capable of going up to about 45-50ºC so taking a standard UV ink, which is 40-50cp and bringing that down to the jetting temperature of about 45ºC to give you your 12cp.
“For these more advanced fluids, they are maybe starting at 1500-2000 cp so we are heating that up to drop the viscosity and in those cases maybe trying to push it up to 50-60ºC to get the viscosity down to the 60-100cp. So you do need an ink system that can boost stuff maybe beyond the normal temperatures of 45-50ºC, you are going up to maybe 60-65ºC to get to the right jetting viscosity, and that jetting viscosity is the 100cp.”
Tweedale adds: “And we have seen for some applications that heating the ink system remotely from the head is the right approach but there are also some where heating within the head is something that’s interesting and we have a development in our road map where we look at heating directly at the channels behind the nozzle plate so really right at the firing chamber.”
He estimates this will take 2-3 years to develop, noting: “It’s not that far away. There are some more complex developments there as well that might take longer but that’s in the relatively near future.”
A further advantage of the printhead architecture and the TF Technology is that it allows printing in multiple orientations, including vertical or horizontal mode, or even when being positioned by a robotic arm with accelerating and decelerating speeds, all of which is useful for some industrial applications.
The Nitrox is available now. Tweedale says that people are already ordering it for direct-to-shape applications, adding: “We have also had a significant number of leads, more than 40 in the short time since we announced the launch of the product, and that’s across a range of sectors, direct-to-shape but also advanced manufacturing and 3D printing so we are really pleased with the interest this has generated so far.” He is understandably reluctant to discuss pricing but does say: “We have different variants and different applications but there is no significant change.”
I think it’s fair to say that the Nitrox is a significant development, giving Xaar a competitive head able to reach the all-important 100mpm speed. It is true that there are higher resolution printheads from other vendors, but for many applications the ability to run higher viscosity fluids will be more important. You can find further details from xaar.com.