Do you believe every spec you read online or in print? When it comes to digital output, manufacturers commit in writing that their production printers and presses can run at maximum rated speeds from 60 to 120 color, letter-size pages per minute (ppm). These numbers, however, beg for some critical thinking: What exactly do OEMs such as Canon, HP, Kodak, Konica Minolta, Ricoh, and Xerox mean by the term full rated speed? And, when an operator reads a machine description that specifies a rated speed, what does that actually tell him or her?
Production speed ratings are best-case scenario performance numbers tallied in optimal, lab-like conditions. To be taken with a grain of salt, these readings are not taken in real-world print shop environments in which different paper may need to be loaded, color is calibrated, operator skills vary, and maintenance needs to be performed over the course of several shifts or even several days. So, what is required to consistently operate a digital press as close to rated speed as possible?
“It’s not so much the optimal, ‘clean- room’ conditions,” says Mike Fego, Konica Minolta product manager for Production Print. “It’s more the paper size and weight” that can limit digital printer and press speeds more than just about any other variable.
It depends, too, on the types of print applications you’re running, of course. “An MFP [multi-function printer] with an embedded RIP, printing a variable data job, isn’t going to be able to run at full rated speed,” explains industry analyst Jim Hamilton, group director at market research firm InfoTrends, where he oversees production consulting services, including production copying and digital printing. But many higher-end devices in the printer-only category, he adds, “claim that they can print at rated speed on all stocks. In a lot of people’s minds, that [ability] is what defines a ‘digital press.’”
Hamilton noted that many MFPs still experience engine slowdowns when they run heavier stocks; some go up to 300 gsm, others to 350 gsm. “Even the next tier of products has this problem,” he says, citing the Xerox DocuColor 8000 line of production printers/copiers as an example. “But now Xerox has a version of the 700 that’s much better;” featuring different speeds for different media. Of the 700’s performance, one printer confirmed, “I run the heck out of it—all sorts of stocks—and rarely does it give me any trouble.”
Konica Minolta’s bizhub Press C8000, some 80 percent of which are being placed in commercial print shops, is one of several OEM models now employing a second fusing station to expedite speed on heavier stocks. Fego explains the underlying science: “In an electrostatic printer with a single fuser unit, the paper has to slow down after the image is on the page, as it goes through the oven.”
Lending its engineering perspective, Xerox added that its xerographic (electrophotographic) dry photocopying technique has a constant speed. “At whatever velocity a given print engine runs, we feed it [paper] at that rate,” says David Mueller, system engineering manager at Xerox.
For Kodak, the NexPress SE 300 runs at its full rated speed—100 A4 four- or five-color ppm—for more than 600 substrates. High-capacity feeders and delivery units, inline solutions, and finishing modules enable even greater uninterrupted printing.
In Hewlett-Packard’s case, the Indigo press can print on up to 18-point substrates without slowing down, largely due to the technology’s oil-based ElectroInk. (There is no oil drying/fusing time required, as in the toner-based electrophotographic (EP) process.)
Many digital devices struggle with coated stock, too. As Hamilton warns, “The more shiny and glossy the paper is, the more of a problem it can pose.”