Ricoh has announced a new MH5320 series of printheads, which is aimed at industrial applications, including wide format graphics and textile printing.
This head has a 54.1mm print width. It has 1,280 nozzles arranged in four staggered rows of 320 nozzles each. These have a 150dpi density, giving it 600dpi resolution for a single colour or two rows of two colours each at 300dpi.
There are three variants, with the MH5320 having up to two colour channels and the MH5340 taking four separate channels, so that it could be set up with a single 150dpi row per CMYK colour. There’s also a MH5320 Type A, which also takes up to four channels but comes without an ink port.
Essentially this new series is a higher spec version of the existing Gen5 MH5420/5440 and the aqueous ink MH5421/ 5441 heads, using Ricoh’s proven approach of a piston pusher with a metallic diaphragm plate. It has a smaller native drop size, down from 7pl to 5pl, and improved jetting accuracy, which according to Ricoh delivers good print quality without graininess.
It can either be used in binary mode with the 5pl drop size or it can be set up for greyscale printing, with up to four levels, from 5-15pl.
But the real significance of this new design is that Ricoh has improved the jetting frequency to 50kHz for either binary or up to three levels of greyscale, allowing for a much higher jetting flow rate, or to put it more simply, increased productivity. This drops to 40kHz for four greyscales but is still a considerable improvement over the older MH5420/5440 heads which have a jetting frequency of 30kHz in binary mode and 20kHz in greyscale mode. This higher jetting frequency has allowed Ricoh to use smaller drop sizes, for better image quality, while still improving the overall productivity.
Ricoh’s standard approach is to use stainless steel units that are bonded together with laminates to form the fluid chamber and ink channels – the MH in the name stands for Metal Head. For this head, Ricoh has improved the bonding technology it uses, which should allow the head to work with a wider range of fluids and operating conditions, particularly in terms of aqueous inks, which is important to the textile market. This in turn should save Ricoh the trouble of developing a specific version for aqueous inks. It’s compatible with UV and solvent as well as aqueous-based inks but Ricoh says that the service life of the MH5320 is more than double that of the MH5421 when used with aqueous inks. The head operates at 60ºC and assumes fluids with a viscosity range of 10-12 millipascal-seconds or mPa-s.
Ricoh has also used a new approach to aligning the heads, based on printhead surfaces, that should make it relatively easy to replace these heads. The head is 89mm long, 24.51mm wide, and 69mm high, which should make it relatively easy for OEMs and converters using the current Gen5 printheads to adopt these new heads.
However, it’s worth noting that this head does not include recirculation, which seems like a backward step for a modern printhead aimed at industrial users. Instead, Ricoh is likely to introduce a separate recirculating version at a later date, as it has done with the current Gen5 heads.
Ricoh will continue to sell the existing Gen5 heads so this is not a replacement for those, but rather will give OEMs and integrators an additional choice. The head will be shown off at the Shanghai Int’l Ad & Sign Expo in Shanghai, China this week from 5-8th March, and should be commercially available from 1 April, 2019.
You can find more details from Ricoh’s website here.