Pharmaceutical and Medical Packaging News
Magazine
PMPN Article Index
Originally Published PMPN November 2005
EDITORIAL
Expand Your Vision
How much of your packaging lines do you want to see? The modern marvels of machine vision can help you keep an eye on practically everything, from unit-dose bar codes to bottle neck diameters, at typical line speeds, say providers. High-resolution camera systems are picking up print and package details with amazing precision. Coupled with the latest software, these systems can gather inspection data and take corrective action, if needed.
But does every station on every packaging line need such monitoring? How sophisticated does it all need to be?
Bob Warner, senior vice president of photoelectric sensor maker Tri-Tronics Co. (Tampa), has a vested interest in the answer. But after working with such sensors for more than 30 years, he sounds beyond the hype. “Camera systems can do a lot more than photoelectric eyes can do,” he says. “But if it can be done photoelectrically, it is pretty obvious. If you are looking for the presence or absence of a critical feature, you can use one sensor to look for that feature and another sensor to tell the first sensor when to sample the feature.” He points out that photoelectric eyes can also be used for checking label or container position, and other critical tasks.
Warner points to a project he worked on a few years ago in the beverage industry. A juice maker wanted to be sure its bottles were oriented properly before filling. Warner provided two photoelectric sensors, one that looked for the “hole” created by the bottle handle, and a second that triggered the first sensor by looking for the bottle’s leading edge. The two cost only a fraction of the cost of a machine vision system. “Some people want to use a camera system when they really don’t need it,” he says.
Given the number of features to be inspected on a packaging line, Warner’s point is a good one. Using low-cost photo eyes at certain points along a line could help stretch a line manager’s budget.
But there are some instances in which a more sophisticated solution is needed. Cognex Corp. (Natick, MA) helped Genesis Machinery Products (Exton, PA) switch from photoelectric eyes to vision sensors for vial stopper inspection. Lawrence Pepper, marketing manager for Genesis, says that “by using In-Sight vision sensors from Cognex, we’ve taken operator subjectivity out of the equation, tightened the tolerances significantly, and improved the process. The vision system isn’t fooled by normal vial inconsistencies, and changeovers now consist of selecting a new job via keyed entry on a touch screen.”
So what does your application call for? John Lewis, public relations specialist for Cognex, recommends trying the easiest solution first. “Customers may start with our Checker sensor, a product for the presence-sensing market currently served by photoelectric sensors,” he says. “If they need more than simple presence sensing, they may try a vision sensor or move to a PC-based vision system.”
Your line may need different systems working in concert to root out defects. You may use insert-detecting photo eyes on your cartoning line with a machine vision sensor a few feet away verifying lot codes and expiration dates printed on the cartons. You may then have another photo eye with a counter over your reject bin to keep track of poorly printed cartons rejected by the vision sensor. Such combinations may allow you to minimize your investment, while monitoring as many processes as possible.
Your packaging line is carrying valuable products—keep as many eyes on it as possible!
Daphne Allen
Editor
Copyright ©2005 Pharmaceutical & Medical Packaging News
