They need lots of data to do their jobs of passing information along so that every operation in the chain can satisfy demand smoothly. These systems are only as good as the data they collect, however. To ensure the accuracy of large amounts of data, more companies are automating the process with vision sensors and radio frequency identification (RFID).

The speed and accuracy of these automatic identification technologies are especially important to medical suppliers such as SynergEyes Inc., a contact lens manufacturer in Carlsbad, Calif. Founded in 2001, the company produces hybrid contact lenses that combine the comfort of a soft lens with the high-definition of a rigid one. Because of the large number of variations in the optics, the company must track tens of thousands of stock keeping units (SKUs).

As the company grew, the old manual method of printing and reading labels became too cumbersome. “We normally make hundreds of different SKUs a day, so the potential for error is very high,” explains Joe Collins, vice president of manufacturing, and research and development. “We had to spend considerable time inspecting each [lens] vial to be sure we had the right label. Even when our company was much smaller, this process was difficult to manage.”

Automation was necessary to prevent any mislabeling that could erode the confidence of customers and lead to expensive recalls. Given the number of labels and the kind of information that must remain with the lenses, the most cost-effective solution was a 4-mm-square data matrix bar code. The 30 to 40 characters in the code include a lot number, expiration date, and, depending on the lens, five to seven optical parameters, such as power and diameter.

Because inspection occurs in a cleanroom, SynergEyes applies two bar-coded labels, a temporary and a permanent one. In the cleanroom immediately after inspection, the strictly utilitarian temporary label is put on the caps of the vials holding the lenses and some solution. After it leaves the cleanroom, a more aesthetic permanent label containing human-readable text is printed and affixed to the vial. Then the vial is shrink-wrapped.

In the old labeling method, trays of vials would come to an operator, who would read the tiny characters on the temporary label on the cap, enter them into a labeling system, print a permanent label, and apply it by hand. Inspectors would then verify that the two labels matched.

Now, a machine-vision-based labeling system designed by code-in-motion LLC, of Irvine, Calif., does this tedious task automatically. A vision sensor from Cognex Corp., of Natick, Mass., reads the bar codes on the caps. The system parses values from the bar code to determine the contents, creates a print file, and sends it to a high-resolution thermal transfer printer. As the permanent label comes off the printer, a second Cognex camera checks both the human-readable and bar code information on it. Good labels are placed on the vials, and bad ones are rejected. Only vials with good labels are shrink-wrapped.

“This automated system has reduced the cost of labeling our products by more than 90 percent,” reports Collins. “Even better, since we began using the automated system, we have not had a single labeling error.”

When the labeled vials go to the warehouse, an operator there scans the bar codes through the wrapper with a Cognex DataMan scanner and places the vials in one of the storage carousels. As medical practitioners in the field order lenses, customer service representatives type the prescription into the inventory management system to find whether it is in stock. If it is, the order goes automatically to the warehouse. The carousel moves around so the operator can remove the vial and scan it to verify that it is indeed the correct lens, and to record the shipment.

Vision versatility

As SynergEyes’ experience demonstrates, bar codes have remained a viable automatic identification technology, despite the hype over RFID five years ago when Wal-Mart and other retailers began requiring their suppliers to use it. One reason is the momentum of the huge installed base of bar code technology that has been in place for decades.

Another reason is a combination of economics and technology. “Bar coding costs fractions of a penny per label,” explains Tom Kahn, product marketing manager for vision and auto identification products at automation vendor Omron Electronics LLC, Schaumburg, Ill. RFID tags, on the other hand, are orders of magnitude more expensive. RFID inlays are available for less than a dollar, and labels containing them can cost ...