Medical Device Link.

PACKAGE PRINTING AND CODING

At MD&M West 2008, Greydon showcased its latest servo flexographic printer.

Rules for printing multiple languages and warnings have increased, and the medical device industry is waiting for FDA to decide whether unique device identifiers (UDI) will be required, too. “We are having to print more labeling information for our products than ever before,” a medical device packaging professional told PMP News at HealthPack this past March. Much of this added text is ending up right on the package, he explained.

As package printing is changing, so are product volumes. PMP News is told that as the number of SKUs is increasing, lot sizes are shrinking. Some companies are offering more product variety and relying on just-in-time production to satisfy orders directly from packaging lines instead of from stock. While these companies are reducing inventory costs, packaging line and printing changeover costs could increase if not monitored.

With more text and codes needed for more packages, companies are pushing their package printing systems to extremes in terms of speed, space, and changeover. “There are more and more rules for information, so printing has to be smaller, yet of higher quality,” says Wil Caraballo, technical sales adviser for Multivac, a provider of form-fill-seal machinery whose users mount printing systems onto its units. “Companies are also performing multiple changeovers.”

Can traditional tried-and-true flexography keep up? Or are programmable printers—also known as digital and specifically involving thermal-transfer, ink-jet, toner-based, or even laser printing—more in line with today’s medical device package printing needs? Can they offer the quality needed?

COMBO OR COMPLETE SHIFT?

Many form-fill-seal packaging lines running these days are equipped with multiple printers. Flexographic printers handle the bulk of the static print, while a programmable printer handles lot or date codes or perhaps even bar codes. This approach has allowed many companies to realize the economies and quality of flexo printing while adding a bit more flexibility.

Some technology providers, however, are sensing a shift. “The percentage of people looking at programmable printing is definitely increasing,” says Greg Rochon, president of Greydon (York, PA). “We are still selling a lot of combo wet-ink flexos with HP’s thermal ink-jet printheads, as well as flexo with thermal-transfer printers, but interest in programmable-only printing is growing.”

Flexography and thermal-transfer printing complement each other very well, says Glenn Breslauer of Bell-Mark.

Jeff Bidlack national accounts manager of Ossid, a provider of form-fill-seal equipment, says, “Typically in the past, programmable-based units have been used exclusively to print variable information such as expiration dates, lot codes, bar codes/Data Matrix Codes, logos, etc. This is changing to include complete printing of packages in conjunction to a registered print.”

Packagers “jumping into program­mable-only printing have shorter runs—perhaps just running at one hour per run,” Rochon adds. “If they are changing over every hour, they just want to be able to touch a key to change product name and text instead of having to mount a new flexo plate.”

Alan Shipman, vice president of sales for ID Technology (Fort Worth, TX), says that “real-time printing needs have increased with demands for complete audit trails of when products are manu­factured and by which production line.” As a result, “thermal transfer overprinter capabilities continue to expand with faster print speeds and changing formulations of ribbons that enable quality printing on more and more substrates.”

Caraballo agrees. “Thermal-transfer, for instance, offers traceability through the use of computer-based programmability. It logs the time and point of printing, important for complying with 21 CFR Part 11. You do not have that ability with flexo.”

Depending upon the area to be printed, thermal-transfer printers can be used to print the entire area of the package and are only limited by the ribbon width and capability of the system used—usually five to six inches, says Bidlack. “For larger areas, multiple printers may be required or used with reciprocating mountings to provide motion.” Flexographic printers can print much larger areas with one common print plate, he says, but employing multiple print plates can also be expensive when producing multiple-product SKUs.

Rochon reports that Greydon’s approach to combination printing has expanded the potential print area for variable printing. The company’s Micromax/HP flexographic printer is equipped with a traversing ink-jet cartridge for in-line printing up to four colors. Presented as an alternative to building a separate traversing system for moving the variable printer across the web, the Micromax allows companies to employ flexography for nonvariable product information and ink-jet for variable codes and text anywhere on the web. Print quality for the ink-jet is up to 600 dpi.

According to George Wright IV, vice president of Product Identification & Processing Systems Inc. (PIPS; New York City), print quality of both text and bar code can be quite good when programmable printing is done using the 600-dpi printhead resolution available on many higher-end systems. He notes, however, that all digital printing is subject to the constraints of imaging system/printhead resolution. “We have to remember,” Wright says, “that most graphic designers have been schooled in a very high resolution environment (2400 to 3600 dpi) where the size of human-readable type and linear bar codes seemed to be infinitely variable and the scaling was always smooth. While 600 dpi is today’s high end for most of the digital printing systems being considered here, there are much more severe limitations on the size of bar codes that can be printed properly than there are with traditional systems where much higher resolution imaging technologies are used.”

Printing bar codes, in particular linear bar codes, where the decoding algorithms all rely on exact edge placement, is Wright’s chief concern. “Too often,” says Wright, “we see failing bar codes printed on digital printing systems that had been “commanded” to print bar codes at sizes the imaging system cannot reproduce. The result is poorly printed symbols that have unacceptable ANSI/ISO print quality grades owing to “arbitrary” bar/space rounding decisions made by the printing system.”

Wright insists on comprehensive image inspection and full bar code print quality analysis. “In a flexo printing process the printing plate is ‘immutable.’ Certainly it can degrade over hundreds of thousands of impressions, especially if the plate is not cleaned at appropriate intervals, but the text, graphic, and bar code “copy” does not change. With certain on-demand digital imaging processes this is not the case. In most digital processes—and certainly any application with serialized bar codes—the bar code is re-imaged with every unit printed. One hundred percent image inspection, data checking, and comprehensive print quality analysis is imperative.”

Providers of flexographic printers do not expect a total shift to programmable methods. Jim Umbdenstock, president of Griffin-Rutgers Inc. (Ronkonkoma, NY), says companies still use traditional flexo. “I do not expect a move to completely digital printing owing to the capital costs,” he says. “Also, companies do not yet have the confidence in digital they have in flexo. In fact, we have replaced a few digital printers with flexo.”

Quint Co. (Philadelphia) supports the flexographic printing industry with quality printing plates. President Ed Howell reports that after visiting a dozen customers using flexo printing, he found that most have no plans to change. “There are too many questions about programmable printing. Companies like the comfort of having a printing plate—at least for the next 5 to 10 years,” he says.

The cost of programmable printing may also deter some potential users. “A gallon of ink for flexo printing costs about $80, and the equivalent amount of ink in HP’s cartridge-based system would be $800 per gallon,” says Rochon. “Programmability comes at a cost, but some companies [will] pay for such flexibility.”

“Thermal-transfer printing often does not make sense for large production runs because it is more economical to print with flexographic systems, given the cost of the consumables,” says Caraballo. “Flexographic printing also has become more user-friendly with servo control systems providing high-quality printing along with disposable ink/cleaner cartridges, which offer a cleaner and maintenance-free method of managing ink.”

A cost analysis can usually expose where the savings will be realized, says Glenn Breslauer, director of marketing and IT for Bell-Mark Corp. “If static information covers the majority of the printed package, flexo inks may be the right technology for the application, where the variable data would be printed by thermal-transfer or thermal ink-jet. If a package is mostly variable, or needs to be changed often, such as those with complex bar codes, then programmable printing might be the wisest choice. Since each provides high-resolution capabilities, either would work.”

QUALITY

Rochon says that flexographic printing offers the best quality on all commonly used medical packaging substrates—Tyvek, medical-grade papers, and polypropylene, polyethylene, and polyester films.

Thermal-transfer printing offers the best quality of all the programmable methods, he says, except on some medical-grade papers. HP’s thermal ink-jet printing is great on paper, but doesn’t give the same quality on Tyvek, he finds so.

Caraballo from Multivac says both thermal-transfer and flexographic printing will provide high-quality print on medical substrates down to 6 point type.

There have been concerns with finding thermal-transfer ribbons appropriate for some specialty medical device applications, especially those involving intense sterilization cycles. “But thermal-transfer offers a variety of ink ribbons capable of printing on many substrates,” Caraballo says. Adds his colleague, Jay Brewer, product manager, labeling systems, for Multivac: “One of our customers had a steam sterilization application and was able to employ thermal-transfer printing. The company matched a ribbon to the substrate and it withstood sterilization.”

Brewer says that there are some substrates that require high-temperature sealing, so “companies have to isolate the heat to the sealing areas only so that the heat does not distort the thermal-transfer print.”