In Part 1 of this article, I covered production inkjet imaging, one of the important differentiators you need to concern yourself with as you try to match your customer and plant requirements to any prospective equipment purchase.

In this article I will look at the other two important considerations; the transport and the DFE. While there are many other features and options that you should be looking at when reviewing production inkjet against your requirements, these three factors should probably be your primary focus.

I am using a similar structure to that I used in the product reviews in order to put it all in context.

Production Inkjet Transports

As we discussed in Part 1, the imaging is what allows you to meet your customer application requirements; however, the transport is what facilitates the actual printing in your production workflow. Just as there is a need for both web and sheetfed offset presses to address the various media, quantities, speed and finishing requirements, the same holds true with production inkjet presses. That being the case, I will break this section down into web fed and sheetfed.

Web fed transports

Web-fed digital presses have been around since the 1970’s, so there has been a lot of time to develop and refine the transport designs. Of course web fed printing has been around for a long time, but inkjet introduces some additional challenges. 

Because of the speed of the web traveling through the press, one of the challenges is making sure the ink drops in the right place on the sheet and doesn’t fly along with the draft of the sheet travel. Once you have achieved that, another challenge is keeping the web flat and dry to ensure good duplexing and ultimately finishing. Since the ink is mostly water based, it can play havoc with the paper, causing bleed through, puckers, stretching, etc. Balancing feed, speed, and drying has been a challenge that all of the vendors have used their creativity to address. Since most print jobs need to be printed duplex, developing a system that would do that in a small footprint was also an area in which vendor creativity had to be applied. There are single engine solutions that can be connected to perform duplexing, and there are twin engine solutions that are built as one unit. The configurations can include straight inline, L-shaped and H-shaped to mention just a few. Like the head technology, in many cases, a press vendor may OEM the transport, or even just the engine from other press vendors.

Of course, speed is usually a major factor in choosing a web press. Throughput speeds run from about 200 ft./min to over 1000 ft. min. and increasing. That doesn’t include the inkjet imprint head modules you can add to your offset web press that now top end at 2000 ft./min. The transports use the imaging engines (printhead systems), and the combination of both, really determine which solution will meet your individual quality and production needs. One additional consideration is the ability to field upgrade the press. Some of the vendors offer field upgrades for additional colors, MICR, speed and duplexing capabilities.

While it would be expected that all production inkjet machines support a wide variety of 3rd party paper handling and finishing options, it is always good to see which vendors and devices are supported.

Sheetfed transports

This relatively new category of production inkjet is designed to fit the needs of the general commercial print service provider. The web solutions that have existed to date are very successful in environments where there is a lot of volume and minimal paper type requirements. However, the commercial printer uses more than 8 different substrates on a regular basis. Trying to manage this with short runs on a web press is not very practical. Sheetfed inkjet presses, especially with the introduction of B2 and now B1 sized presses fit the sweet spot for general commercial printers.

Feeding a lot of different papers through a press is a lot more difficult than most people realize; just ask an offset pressman. Whether you are using a lightweight uncoated stock or a coated board sheet, getting the paper to feed with precision at a high speed requires significant engineering. Offset presses usually will use a gripper to pull and a side guide to align the sheet into and through the printing system. Many electrophotographic (EP) systems use belts and/or vacuum to transport the sheet. They can get away with that since they don’t need to support the plethora of sheets and board that an offset press may encounter. If you add duplexing to the mix, you have just added many levels of complexity, including drying, flipping heavier stocks, front to back registration, etc.

Since sheetfed production inkjet is a relatively new category of press, we are beginning to see a lot of different variations of design. To date we have seen the offset gripper/side guide model, a vacuum transport, some new patent pending transports, and after drupa the designs will undoubtedly increase. The most important factor here is to look at the work you currently do and plan to do in the future, and see how each of these transports will be able to support your needs. For the most part, paper size and thickness specifications are readily available. However, operational performance in different environmental conditions can present differing results. So pay attention to their facility recommendations. This is especially true in presses that duplex. As we have discussed throughout the series, other issues you need to be aware of are the potential need for, and availability of, pre-coating, and drying that will support your desired paper requirements and ink coverage levels.

Digital Front Ends (DFEs)

This is probably one of the most misunderstood yet most critical parts to any press configuration. The best imaging and transport system can only deliver what gets processed in the DFE. If the DFE isn’t up to the challenge or configured improperly, you are out of luck.

At the base level, file type input is very important and usually dependent on your type of work. PDF/X-4 is the default requirement format, since support of other PDF/X variants would also be available. However, if you are producing variable data documents, you will need to support PDF/VT and AFP/IPDS. Color management support is usually a given, but being able to create color characterized paper libraries is almost a necessity, but not always there or easy to find.

Since most companies don’t have the luxury of starting their company with a clean slate, one of the issues many printers have trouble with is integrating this new press into their existing workflow processes. While many vendors promise ‘JDF/JMF inside’, there are varying levels of implementation. In todays demanding production environment, it is important to look at how your new press will integrate upstream with your MIS system and through dotted line to your existing production systems. Otherwise you are destined to create inefficient and expensive workflow silos. Of course, there are third-party products that can glue some of these together after the fact, but that may not be the best solution. Much better to address these integration issues before you make the purchase decision.

Finally, when working with variable data, both the DFE and your plant infrastructure needs to be designed to handle the volume of data that will flow through it. Many of the included DFE solutions are built with scalable architecture to allow you to grow the solution through the addition of additional CPU’s, RAM, and RIP instances to process the data at a minimum of press speed. This is especially important for the web-fed machines due to their high speeds. If your plant is not currently doing variable print, it is also important to look at your plant data infrastructure to ensure that it can support this new capability.

In conclusion

drupa will bring many additional announcements in both the web fed and sheetfed production inkjet category. We have already seen announcements from offset press manufacturer KBA about its partnership with RR Donnelley and its entry into web fed production inkjet, and we already know we will see a sheetfed offering from MGI, and from Landa, in both the sheetfed and web category. And I am willing to bet there will be many others as well.

While this series has been dedicated to looking at production inkjet technology and presses, we can’t forget that there are other viable, quality, productive print technologies out there. These include offset, EP, and the increasingly growing category of Liquid Toner Sheetfed, once the sole domain of HP Indigo and now being introduced by Ryobi/Miyakoshi, and the new Xeikon Quantum technology. However, probably the most exciting news in all of this for commercial printers looking for digital sheetfed technology is that most of the sheetfed solutions will be available in B2 and even B1 sizes offering the production flexibility necessary to support the new on demand and variable print service provider market requirements. And you don’t need to go it alone. There are many resources out there to help you prepare, make the right decision, and work with you to implement any solutions.