One fascinating property of inkjet is its ability to print on almost any substrate – with the right inks and transport as a prerequisite. Metal is not the newest substrate for inkjet, however, mainstream adoption is just about to start.
The most likely use case for metal printing is in packaging. A great number of containers are made from metal (usually steel or aluminum). There are additional applications in decoration or protection (metal covers). Potentially all kinds of metal objects can be printed directly by inkjet but this is still an area even further out on the adoption horizon.
Metal packaging is creating more interest in an increasingly sustainability sensitive world. Metal is indefinitely recyclable, as opposed to paper/board, where fibres get lost, and especially as compared to plastics, which can usually only be downcycled or incinerated due to collection and sorting issues. At the same time, metal packaging is seeing the same dynamics as all other packaging markets with shorter runs, customisation, streamlining of supply chains, and shorter production cycles. The recently held MetPack show in Essen, Germany provided a great overview of technologies used in metal packaging. Overlapping with Interpack 2023 in Düsseldorf, the show sported more than 300 exhibitors focusing on metal packaging and decoration equipment.
Inkjet printing on sheet metal
Today, mainly modified offset presses are used for sheet metal print. Presses are pricey, ranging from €1.5 million (1.64 million USD) for a single colour press to €10 million (10.94 million USD) for a full-blown, automated line with multiple print units. They can be huge as well, with a conventional drier taking up 39m of length. UV presses are much shorter. Due to the susceptible substrate and drying effort, the presses require dedicated feeders and are not operated at speeds reached in paper or folding carton presses. Usually 6,000 to 8,000 sheets/hour are the top speeds achieved. In turn, this means that the speed difference between inkjet and conventional print is not as high as in commercial or packaging print, making single-pass digital solutions more viable.
SACMI, the Italian producer of machinery for ceramics, packaging and beverage markets has considerable experience in ceramics inkjet printing. SACMI introduced a new metal printing inkjet press at MetPack, the DMD 1408. This is SACMIs first full-size model for sheet metal print to serve the standard metal sheet format of 1,000 x 1,200 mm. This format has been set by conventional presses and is demanded in existing converting and finishing lines. A smaller size version of the DMD was already installed at ASA group in 2020, a leading metal packaging producer in San Marino.
The press uses UV inkjet and Fujifilm Dimatix print heads with a resolution of 600 x 1,200 dpi, which brings the quality very close to offset. A vision system is included, and the quality demonstrated looked very good. Food-grade inks for the press from Sun Chemical were Introduced at MetPack which should open food packaging markets. As part of an open ink model, additional ink manufacturers are possible. So far, the press uses four colours but a seven colour version will become available. A digital varnishing unit is already available as an option.
The DMD Line can process up to 2,400 sheets/hour (although at lower print resolution) and SACMI reckons that the breakeven against offset will be in the 1,800 sheet range. The DMD line was shown printing congigured in a basic version without automatic feeder and delivery. A fully automatic sheet transport option will be supplied by partner Inghor – an established provider of sheet metal handling solutions. SACMI is undertaking a controlled release of the product with a second unit targeted to ship in September and a third line before year’s end. Full availability is planned for 2024.
SACMI DMD1408 at Metpack 2023
More options available
There was more news at MetPack 2023 as Barberan announced a version of their established Jetmaster-Series for sheet metal printing. Barberan has more than 100 lines sold globally. They are expanding into metal print after the successful installation of three lines in Korea printing on metal unwound from coils. With the inherent LED-UV inkjet technology, 600 dpi imaging resolution and substrate flexibility of the Jetmaster line the main adaptation is a new sheet transport. As Barberan has an open ink model, customers would need to select inks that adhere well to metal and are temperature resistant in an autoclave (where needed). There are three models available from 1380 mm to 1840 mm width, all able to support the standard 1,000 x 1,200 mm format for metal sheets.
Metal coil processing specialist Bonak, also from Spain, featured a concept for a sheet metal inkjet printer at their MetPack booth as well. The printing line is supposed to work with aqueous inks and a maximum resolution of 720 x 360 dpi with 4 grey levels. With a printing width of 1250 mm and a 80 m/min speed, it would be targeting the mainstream market. Still, there is no product name and little information was available at the booth, making it unlikely that the first installation will take place as indicated in 6 to 12 months’ time.
There is more choice for sheet metal printing from bespoke inkjet press manufacturers such as Neos. The company showed designs targeted at metal print at MetPack based on increased customer interest. Neos also developed a new ink for metal print which can be deformed well in further processing.
Market leader in conventional metal print Koenig & Bauer exhibited only conventional technology at MetPack. The first inkjet metal printer concepts Koenig & Bauer previewed in the past, have been shelved. Still, Koenig & Bauer sees a big opportunity for inkjet and is working on new products. To keep the entry hurdle low, a multi-pass inkjet printer is planned for the end of the year as a joint development with Durst. A single-pass inkjet press is on the roadmap and likely to follow later, without releasing any details so far.
Inkjet for can printing
For printing on cans, traditionally dry offset print is utilized. Newer presses can reach a speed of about 2,000 cans per minute. The low degree of automation, even in newer presses, means that change-overs are long and costly. This leads to minimum orders in the range of more than a million cans from the major can producers on traditional print equipment. Consequently, metal can printing is seeing a big push towards inkjet in recent years. The uptake has been slow, however. Vendors like ToneJet, SLAC, Hinterkopf and Velox sold single units only. Inkjet Insight author Sean Smyth recently covered the market developments for can printing.
MetPack offered some progress in the inkjet can printing sector as well. German supplier Hinterkopf presented their Generation 4 models. The complete imaging unit has been redesigned and the imaging resolution has been lifted from 1,200 to 1,800 dpi, which allows for micro-text down to 2 points and offset-like quality. Up to nine ink channels are available for up to seven colours plus white and varnish. As before several models differing in speed and automation will be available, ranging from 120 to 240 containers per minute as output speed. The Generation 4 system is in beta testing for one year and will become fully available in 2024.
The Israeli startup Velox exhibited at MetPack as well, showcasing the top productivity IDS Series (although not live at the booth) for container printing. The top model can print up to 500 containers per minute, which is considerably narrowing the gap to analog. The press has up to 14 colour channels and can switch between matte and gloss. The resolution is 900 dpi on Ricoh Gen5 heads. Velox supplies its own patented inks and proprietary container transport and print technology. Very interesting is that the technology allows printing on the neck of the can. So far three printers are at customer sites with the first one enabled for neck printing shipping soon.
Inkjet can printing does not necessarily require high-end equipment. At FESPA 2023 Inkcups introduced the first desktop can or container printer with the HelixOne. The UV printer has a maximum resolution of 600 x 1,200 dpi and offers white and varnish as options. Designed for the occasional user or at point-of-sales locations, the printer has a low investment point of about $75,000.
Inkcups Helix One at Fespa 2023
Enabling inkjet metal print
The use of inkjet in metal print is only at the start. Single-pass presses for sheet metal start to become available and can printing is gaining traction. A lot of reluctance is still based on the existing business models, which are optimised for high volume production – from printers and brands. This is about to change, although experience in other inkjet application areas, such as book printing, means that it will take years.
There might be some technology hurdles as well. Almost all inkjet presses in metal print use UV inks so far. This allows for a quick and compact drying but in food packaging UV inks are still a contested field – although metal has perfect barrier properties for prints on the outside of a container.
It seems there is still work needed on the availability of inkjet inks for metal print. Foremost they need to bond well to metal and often be food safe. Additional requirements exist on being able to bend, resist high temperatures or allow controlling gloss levels. Additional colours and special effect inks will be needed as well. Prices of inks are high as developing new inks is costly and volumes are (still) low.
Opportunities are good however and are not just limited to replacing existing analog equipment. Inkjet can make metal printing more widespread. Metal can printing is concentrated in a handful of very large corporations. Sheet metal print capabilities are a bit more widespread but due to the cost and size of a metal print offset press the number of sites is limited – with about 1,000 sites worldwide. With a lower investment, simpler operation and aiming at underserved demand in metal print, inkjet can make the production technology much more accessible.