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Sat, Aug

ON TEST: EFI GS3250LX

At 3.2m wide, this is one of the biggest wide-format machines to offer LED curing at a speed suitable for high-volume production environments. Nessan Cleary puts it through it’s paces.

LED curing is becoming increasingly common, particularly amongst smaller printers though many people doubt that it can be used with the bigger, more productive machines. So EFI caused a stir when it first announced the 3.2m wide GS3250LX, one of the biggest UV wide format printers to use LED curing. With around a hundred already installed in the UK, it's obviously proving popular.

The GS series is designed as a workhorse machine, targeted at high-volume users. As with most Vutek printers, it’s a hybrid design that’s essentially a roll-to-roll printer but with tables either side to support rigid media. There’s a choice of two sizes - 2m and 3.2m wide - and between LED for the LX Pro models and mercury curing. There’s also a dedicated roll-to-roll version, which comes in both 3.2m and 5m widths. EFI says that this particular model, the 3.2m wide GS3250 LX Pro, can produce up to 111m2/hr or around 32 1.2 x 2.4m boards.

The printheads come from Seiko, and have a fixed drop size but with a choice of 12 or seven picolitres - EFI calls the latter option Ultradrop. There’s a choice of resolutions between 1000dpi, which uses the native drop size, or 600dpi, with either a fixed drop size or greyscale. EFI achieves this by firing multiple drops which combine on the media to form a larger drop size - 21 picolitres for the seven picolitre head and 24 picolitres for the 12 picolitre head.

Amira Bouchiba, marketing and demonstrations manager, says: “The 7pl makes a big difference especially in the smaller text. It can go down to 3pt without problem. Also it's better for skin tones and gradients.” However, she says the fixed drop size is better for solids and that most customers are happy with this setting.

The printer takes eight colours plus two channels for white, which comes as standard. It’s normally loaded with CMYK plus a full set of light cyan, light magenta, light yellow and light black. But it can also be loaded with two sets of CMYK to double the throughput.

The ink is supplied in five litre containers. These sit just below the capping station in a cupboard on the left of the machine. The bottles are weighed so the system knows how much ink is left and the operator can set whatever threshold they like to generate a low ink warning.

LED curing

All of the curing is done through LEDs, with two LED units located either side of the print shuttle. Bouchiba explains: “In order to be able to cure the ink decently with LED we are using nitrogen to eliminate the oxygen on top of the material for better curing. The printer has a nitrogen generating machine. It takes the nitrogen from the air and passes it over the zone. It's totally safe. It’s next to the LEDs where you might normally put anti static bars and continuously sprays while you print.”

EFI claims that the use of LED curing has significantly reduced the power consumption of the machine, by around 80% according to a report from Fogra. This is partly because the lamps don't need to heat up or to stay on. Bouchiba adds: “The LED still needs fans but they are not on as much as with a mercury lamp system.”

The reduced heat means that you can print on heat sensitive materials. But Bouchiba says there are other benefits, explaining: Because of the LEDs there's less heat in the machine so all the parts, like the cabling, that used to suffer after a few years now last longer.

Loading and maintenance

The printer takes media up to 5.08 cm thick and up to 3.2m wide. It’s possible to print two rolls side by side, though they’ll need to be the same thickness. There’s a sensor in the dancer bar that automatically measures the thickness of the media and the print shuttle has a sensor to detect where the media is on the bed.

The bed within the printer uses a vacuum to hold the media, and the whole system is driven by a belt to move the substrates through the machine. There’s no need to keep the roll media under tension, which means that the substrates can be printed before being attached to the take-up roll with no waste.

There are buttons on the back of the printer so that an operator can advance the media, turn the vacuum on and off or print the job so that it’s easy to load rigids from the back.

The machine needs daily maintenance - wiping the heads with solvent - at the end of each day or shift. It’s a manual wipe but there is automatic cleaning during the day. The capper tray has a filter that removes excess drops and that needs to be cleaned each day. The beam needs to be oiled on a weekly basis and there are various filters that need to be changed every few months, depending on ink consumption. There's a solvent cleaning line stored in the capping station, plumbed right into the machine for dealing with badly clogged nozzles. You can plug this into the ink line to blow solvent through the head if there's a clogged nozzle.

Pricing

The basic cost of the machine is around £290,000, with the 12 picolitre heads. The seven picolitre Ultradrop heads add roughly another £30,000. The price also includes delivery and installation, as well as whatever training is necessary, which can vary from customer to customer. Robin East, managing director of CMYUK, says that there is a lot of flexibility in pricing depending on configuration.

EFI also supplies a Fiery XF Pro server, which comes with an X-Rite i1 spectrophotometer and a license to make your own profiles. It can also map around tricky spot colours and also has drivers for other vendors printers so it can be used as a centralised production hub. This costs around £10,000.

On test

Our standard test consists of two A0-sized charts, one with mainly solid Pantones and one with mainly photographs, both of which we print at the machine’s highest resolution, to gauge the print quality it’s capable of, and at a standard production mode, to see the sort of productivity and image quality you can expect on a daily basis.

For this test we visited CMYUK, EFI’s main UK distributor. The machine was set up with a full set of light colours and fitted with the Ultradrop printheads.

For the high-resolution images we used the Best Quality of 1000 x 720dpi, bi-directional printing with heavy smoothing and maximum curing. Both charts printed in 4.25 minutes each, and each used 12.77 ml of ink. For the production test we opted for the POP mode with 600 x 300dpi, with a fixed droplet size. This was faster, with each chart taking 1.27 minutes to print. However, the solid Pantone chart used 30.02ml of ink, while the photographs took 24.14ml of ink.

There's very little difference in the image quality between the two print modes. The solid Pantones are identical though the colours appear slightly more saturated in the higher resolution print of the photographic chart, though the difference is so slight that this could be down to the profile laying down more ink.

The higher resolution images are slightly sharper, though not by as much as might be expected. The text is easily legible down to four points in the 600dpi images and just about readable at three points, whereas with the 1000dpi images the three point text is more clearly legible, but there's not much in it.

In all cases, the printer has put down a lot of ink so that you can quite feel the ink ridges when running your fingers over the print though Bouchiba says this can be improved with better profiles.

Conclusion

In conclusion, the GS3250LX Pro offers a lot of printer for the money. It’s certainly fast enough for high production environments with no need to wait around for lamps to warm up. The results are excellent, with plenty of shadow detail and the colours appear crisp and exactly as expected. The images from the POP mode are easily good enough that most people will simply use this for the majority of their work.

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