A sequel worth the wait

Clocking up near 40 years working in the printing industry, I am still intrigued with either what we can print or even more interested in what we can print on. I attended a seminar recently on 3D printing with metals, it is known as direct metal laser sintering or additive manufacturing. However, the question is: ‘is 3D printing really printing?’ I ask this question as building shapes is not the primary purpose a printer has.

I feel our representation of the word ‘printing’ is spreading a message. After all this was one of the reasons Gutenberg found instant success coming at a time when a very special message from Luther was eagerly anticipated and demanded. Our ‘messages’ are vast and varied from POS buy me now posters, annual accounts, and newspapers; all of our printing is about getting information, in any form to the audience.

 What I think is far closer to 3D printing is the ability to apply our message to any surface. Traditional printing is founded on applying pressure to transfer ink to a flat surface and more recently digital inkjet printing pulses ink onto a substrate. It is this ability to fire ink very accurately that I feel leads us to be able to produce what is ‘really’ 3D printing.

We are also seeing a number of advances in the field of drying in the form of LED UV and coupled with new UV inks, we are able to print on a vast array of materials that previously would not have been possible.

Mimaki have pulled together their expertise in both of these fields to produce a stable of printers that will allow you to print on virtually any material or shape, providing it is has a height less than an incredible 153mm, they have two printers that can deploy your message.

Whether the material is wood, leather, glass, plastic, canvas, aluminium or vinyl, one of the two printers, the Mimaki UJF-3042 MkII or UJF-6042 MkII will be surely able to print on it.

Clever design

The printers differ in size but have a similar, virtually identical, construction. There is a bed to hold whichever substrate you wish to print on which is either 420 x 300mm on the UJF-3042 or wider at 610mm in size on the 6042.

Both machines have their ink reservoirs sat above the main carriage each with the capacity of up to one litre and can be easily changed by the operator with even a cleverly placed sponge in front of the bottles to avoid drips from empty bottles.

They have a large hood that covers the work area which ensures both a secure and chemical free working environment for the operator, but also controls the workspace so the substrate or object placed on the bed has the deployment of the inks matched accurately and in place.

It is not only the environment that can affect the final position of the projected ink; the initial positioning of the inkjet heads is also paramount. To ensure this is replicated accurately Mimaki have designed the heads to be moved on a recirculating ball leadscrew. This device, which is extensively used in machine tools and precision equipment, means the print heads can be placed within 0.01mm.

Both machines use a range of three UV inks: LH100, LUS120, and LUS150. The LH100 is a rigid ink with good scratch and chemical resistance making it best suited for outdoor applications and small goods. The LUS120 is an extremely flexible ink that can be increased in size by 170 percent, making it useful for printing on PET film, leather, and TPV as it has a very low curl property. Finally, the LUS150 sits neatly between the other two making it a good choice if cut or finishing processes are needed.

Both printers have at their heart a piezo-electric inkjet print head in a unique staggered set up. The UJF-3042 MkII has three sets of heads with one white head staggered from the other and the UJF-6042 MkII a fourth head with light magenta and cyan inks but also with the staggered white head. The staggering of the white head allows for the white inks to be applied in one pass, increasing productivity.

Green goals

With the need for traceability or compliance, these inks are underpinned by the Greenguard gold standard.

Greenguard certification is part of UL Environment’s ecological compliance program. UL Environment is part of Underwriters Laboratories (UL) and acquired Greenguard in 2011, which provides purchasers with assurances the products being supplied will perfectly comply with the highest of worldwide ecological standards.

To satisfy the Greenguard gold standard, the inks supplied by OKI must meet the stringent emissions standards based on established chemical exposure criteria. Specifically the LH and LUS inks meet the UL2818 standard, which is for low chemical emissions for indoor production.

To ensure a stable deployment of the white ink used, both models include a circulation system that ensures any sediment does not build up in the ink system channels. This system ensures the white inks that can be prone to inconsistency due to sediment are kept consistent and so can produce bold deep colours when over printed.

Productivity levels range between 2.48cu m/h at 600 x 600dpi on the UJF-3042 in draft format and at a higher 1,200 x 1,200dpi output is 0.89cu m/h in a high quality mode. The UJF-6042 ups the ante at 3.52cu m/h and 1.28cu m/h in the respective modes. There is a 20 percent productivity increase compared to the earlier models.

Ink deployment is enhanced by another Mimaki gadget, Mimaki Advanced Pass System (MAPS). MAPS disperses the ink pattern on the sheet in a very specific array to allow the even drying of the product. There is also a Nozzle Check Unit (NCU) which checks and cleans each nozzle automatically but if the cleaning process has not been successful, the Nozzle Recovery System (NRC) monitors and swaps nozzles when any become clogged or blocked.

These systems can also produce a range of finishing by applying matte, clear, and even textured varnishes. Considering the design, I suggest the UJF-3042 MkII or UJF-6042 MkII printers are truly 3D printers.


Brian Sims, principal consultant, Metis Print Consultancy, www.metis-uk.eu

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