Since this story is a direct follow-on to last week’s story about new printheads, it seems sensible to start with Konica Minolta’s new KM1280iMHH-S, as discussed by Paddy O’Hara, director of business development for Industrial Inkjet, or IIJ.
Most of Konica Minolta’s printheads produce either large drops at 100-400dpi resolutions for coding and marking applications, or small drops at 600 to 1200 dpi for high quality graphics. So the KM1280iMHH is designed to fit in the middle of the portfolio, producing 450dpi with a medium drop size from 1280 nozzles. The first release will be a version for single pass variable data applications, where it can produce large enough drops for higher speeds, but with enough resolution for fine text. It can also be used to print white and spot varnish as well as for direct to shape printing, and materials deposition uses.
This series of heads will feature a silicon nozzle plate for better drop accuracy at higher speeds. It has a print width of 72mm, with 450npi, able to produce a native 10pl drop volume with a typical firing frequency of 40KHz. It can handle solvent, oil, UV and aqueous inks, with a viscosity of 7-12mPa•s and theres also an option for an internal heater. It also has the same footprint of the KM1024i series and uses similar drive electronics so that it should be possible to integrate fairly easily. It’s due to be available next year.
O’Hara says that IIJ has been working with Konica Minolta for around a dozen years, both supplying these printheads to the UK market and using them to develop a range of inkjet print modules. He described how Konica Minolta found after taking over the Panasonic printhead business that Panasonic had been tuning wave forms for every head, for each colour for every customer, adding: ”That’s insanity. Konica Minolta produce robust waveforms that work for a range of applications. Being able to work with a wide range of fluids makes integration easier.”
He says: “The heads have built-in heaters and can handle a range of viscosity.” He points out that Konica Minolta developed a gel UV ink for the AccurioJet KM1 and that this will now be available to other OEM customers, noting: “It’s more complex than a standard ink system so there will be a little bit more support.”
O’Hara questioned what sort of features people should look for in a print head, saying that not every application needed high resolution. He added: There’s a demand from the market for cheaper. But this stuff is cripplingly expensive to develop and to make perfect so a constant question of cost per nozzle will squeeze people out of the market.”
He says that one of the guiding principles at IIJ is to keep everything as simple as possible, adding: “The more complex a system the higher the R&D costs and you will be later to market. And the more complex the system you build the more potential for things to go wrong.” Thus IIJ keep the heads together and avoid pining between colours to create very compact print modules.
O’Hara then went on to make a good argument for using compact printheads, pointing out that the Konica Minolta heads do tend to have a fairly small footprint. This matters in scanning applications, such as wide format printing, because it makes for a smaller print shuttle. This in turn helps to cut the cost of the printer, as its easier to move a smaller shuttle, and it also leads to better bi-directional print accuracy.
Using compact printheads also helps with direct to shape printers as it allows for a smaller distance between the rows and therefore the ability to print to smaller radiuses. And, of course, the smaller the overall printer, the cheaper it is to build it.
There’s an even more compelling reason for using compact heads on a single pass web-fed printer as it reduces the risk of movement of the web between the colours. Naturally, the more compact the print unit, the easier it is to retrofit it to an existing machine. IIJ has used the Konica Minolta printheads to develop a highly effective range of print modules, including four-colour units that are not much bigger than some monochrome units. O’Hara says this is partly because keeping the heads close together means there’s no need for an arch design, and no pinning between the colours, which also saves on cost.
Tom Roetker, vice president of engineering for Memjet, also spoke about the importance of thinking about where the print system has to fit into, saying that sometimes various factors dictate where you have to use the printing in the manufacturing chain but that increasingly customers are looking for more flexibility to bring the printing closer to the point of use as well as a growing demand for late stage customisation to packaging.
Memjet uses a MEMs approach and in recent years has invested into its core technology to add a number of new features, including a bonded heater and integrated temperature sensors as well as improving the design of the firing chamber and the fluidic channel. The bonded heater has improved the drop size, while improvements to the refill rate for the chambers leads to straighter drop ejection.
This has resulted in improvements to the drop placement accuracy and the consistency of the volume of each drop. Memjet has also managed to significantly increase the number of redundant nozzles, which in turn directly contributes to a longer lifespan for each printhead.
Memjet has used this technology to develop two platforms: Duralink, a high speed single channel printhead that I’ve already covered here; and DuraFlex, a four colour version aimed at lower volume applications, which I’ve written about here. They both use an aqueous pigment ink and have 70,400 nozzles, delivering a 2.1pl droplet from a firing frequency of up to 15.5 KHz.
The DuraLink heads can be staggered, with up to 12 heads to create a 2.5m wide printbar. These printbars can be stacked eight deep to allow for up to eight colours. Memjet supplies the ink, and has just released orange, green and violet, alongside the existing CMYK to create a seven-colour inkset. Since the DuraLink heads only jet a single colour, Memjet has been able to dramatically increase the nozzle redundancy. Memjet also uses a closed loop tone compensation, which automatically recognises problems in printed images and corrects the output.
The DuraFlex design offers a much more compact solution, with a choice of A4 and A3+ wide heads, that can be staggered to create a single print bar up to 1.2m wide that supports up to four colours. Roetker says that giving customers the choice of the more compact DuraFlex system means “they can put it where they want to put it and not where we told them it should go.”
Roetker says that using a MEMs manufacturing process is important to the print quality, noting that the DuraLink heads are capable of jetting 4 micron at 3 sigma drop placement, adding: “We have very consistent drop placement accuracy.”
He says that Memjet has also built in a certain amount of maintenance, saying: “Everything is automated so we can do a clean at the start of printing.” This has helped to extend the lifespan of the heads though printheads do still have to be changed. He says that it takes about two minutes to align a printhead, explaining: “We drive it through a camera system and can adjust a printhead to within five microns accuracy.”
Roetker says the key to Memjet’s success is to approach the whole system from the printhead all the way through to the whole product. He adds: “We looked at the ink as also being an eco-system component. There is an ink to media interaction so we decided that we also want to help customers develop primers and other things that help with different media.”
This allows other vendors to integrate the Memjet solution quickly into their products, so they can get to market faster with reduced costs. Memjet supplies the printhead module complete with maintenance, ink supply, waste management and software interface, while the OEM has to put together the printer chassis, plus any additional drying and a bulk ink supply, along with calibration and quality control, RIP and workflow.
Taking a different tack, Richard Darling, in charge of strategic business development at Ricoh Europe, made an interesting pitch that suppliers should work together more and worry less about NDAs, which some of the vendors I spoke with were less keen on. But Darling did make a serious point that inkjet technology is still only barely penetrating most industrial markets despite the huge sums of money that have been invested in it. He said: “People aren’t interested in drop size but in how they make money. Unless we deliver a return the investment in this technology will dry up.” He added: “If we continuously want to work on the extra 10 percent of performance that costs 90 percent of the budget without delivering something then we are missing a trick.”
He suggested that it would be better to educate customers to make use of the existing technology and to understand the inherent advantages of inkjet production, rather than simply seeking to replace conventional systems. And he shared examples where the use of inkjet allowed better inventory management so that there was less need to match conventional production speed.
So far I’ve only drawn on some of the plenary presentations from the start of each day. But there were a great many more presentations covering the different aspects of printhead design, ink chemistry, software and so on that together play a part in an inkjet printing system. I’ll come back to some of these presentations in further stories over the next couple of months dealing with issues such as waveform design, recirculating ink past the nozzles and the use of MEMs architecture as well as Xaar’s work in jetting high viscosity fluids and Fujifilm’s Samba Printheads. In the meantime, I’d suggest that anyone interested in these stories might want to consider attending next year’s IJC – you can find details at theijc.com.