RFID Labeling Lines Need More Speed

Imagine having just completed a multimillion dollar project to automate a pack-and-ship operation when the boss asks if the line can be retrofitted to print and apply smart labels instead of bar code labels. Then, you discover that the rate at which these smart labels can be applied will force you to slow down the line. This is a real dilemma for many high velocity operations that have been asked by Wal-Mart and others to help drive the migration to RFID ubiquity. To put this in perspective, lines capable of printing and applying bar code labels can operate at speeds approaching 100 boxes per minute. With today's smart labels, 60 boxes per minute is the top end, while 20 to 40 boxes per minute is the norm.

To learn how the industry is addressing this challenge, I spoke with several providers and implementers of high-speed print-and-apply labeling systems (namely, Avery Dennison, Accu-Sort, Printronix, and The Kennedy Group). These companies are working to resolve two issues: the quality of finished label stock, and the extra time required to read, encode, and verify RFID tags during the print-and-apply process.

The fundamental limitation to line speed is yield on labels. "Detecting and ejecting bad labels is where you get killed," explains Printronix CEO Robert Kleist. Although good progress has been made in this area (yields used to be around 60%), 93 to 96 successfully encoded labels out of every 100 still isn't good enough. "We publish two speed ratings for our SmartOne line of printer/applicators – with and without the label eject feature," explains Joe Jiner, director of RFID development at The Kennedy Group. Based on these ratings, ejecting just one bad label every minute reduces throughput by as much as 20%. Imagine the implications of ejecting three or four bad labels per hundred.

The label yield problem is exacerbated by the fact that RFID reader/encoders need to work with a variety of labels based on different chips and myriad antenna designs. "The issue here," explains Dan Williams, marketing manager at Avery Dennison Printer Systems, "is the ability to find the sweet spot on the label." The printer companies are addressing this issue by testing different labels with their printers and developing firmware that will allow end users to tell the printer what kind of label stock is being loaded. Based on that information, the printer will adjust for optimum RFID tag encoding.

In addition to the label yield problem, it simply takes longer to print smart labels than regular labels. The process of reading, encoding, and verifying the RFID tag adds 200 to 300 milliseconds to the process. This all has to happen before you print anything on the label. To make up for this delay, printer manufacturers need to increase print speeds from 10 ips (inches per second) to 16 ips, and also negotiate the bump in the label caused by the RFID chip. Chips based on the Gen 2 specification should help to address this issue by dropping the time required for read/encode/verify to 20 to 30 milliseconds.

As the technologies mature to address both the label-yield and time-to-print impediments, other approaches are being pursued to maintain line speeds. For example, Printronix has implemented several "in series" solutions where the second encoder/printer/applicator picks up the boxes missed by the first station, or each station picks up every other box. Avery Dennison will provide preprogrammed and preprinted labels that can be applied with a high-speed apply-only system designed specifically for that task. In the meantime, cardboard box manufacturers are working on putting the RFID tags directly into the cardboard, which would eliminate the need for a smart label altogether. But that's another story.