Vision Sensors Scrutinize Bottle Labels

Success in the marketplace depends on flawless product quality and attractive presentation. Because the customer is always right, producers have to do everything they can to encourage the purchase decision.

Given the pace of modern life and the everyday deluge of visual stimuli, consumers' purchase of food and drink products no longer depends exclusively on the quality of the contents. The design and functionality of the packaging has to make the product appear appealing at first glance. Producers must also take into consideration many other issues such as logistics, regulations, company procedures and industry standards. 

The latest packaging and filling lines operate at ever-increasing speeds. The demands made of the packaging are becoming more complex, and potential defects have to be completely ruled out. Because of these increasingly strict requirements, manual inspection is no longer a viable solution.  

In many sectors of industry, high-performance machine vision systems have become an essential part of the production process, for quality control in assembly and material flow environments. These systems are now being deployed throughout the food industry, from the major international players to small independent businesses. 

Vision sensors serve as small, compact and fully autonomous image processing and analysis units. Because vision sensors are relatively inexpensive, and quick and easy to install, they are steadily asserting themselves in the market. Among the many applications of such all-purpose vision systems are label printing and barcode monitoring, pack inspection, vacuum testing, quantity checking and cleanliness inspection.

Optimizing the entire process
For many years CLK, an innovative German company, has specialized in machine vision and quality control systems. These systems are integrated into complete production monitoring solutions that are designed and supplied by CLK. The main element of these installations is image processing and analysis software, which is customized according to the specific requirements of each customer. 

Dr. Stefan Leppelmann, the company's Managing Director, explains, ‘‘Our work starts well before implementation. We are constantly aware of the entire process. We help the customer during the planning stage and with defining the specification.’‘ 

CLK serves its clients as a development partner, to ensure that the systems they supply integrate seamlessly into existing production and packaging lines. The company's skills extend well beyond the machine vision technology, by taking into account all the implications of the inspection systems on all aspects of the customer’s manufacturing processes. This includes selecting the most appropriate hardware, lights, cameras and optics. In addition CLK liaise with the machine builder, who takes care of the product feed and positioning devices.

CLK installs PC-based vision systems as well as In-Sight vision sensors supplied by its strategic partner, Cognex, the world's leading machine vision company. Cognex advanced image processing algorithms are universally acknowledged to provide the most reliable inspection solutions available anywhere. The companies In-Sight systems can be used in a wide range of different applications by taking advantage of the built-in library vision tools and Ethernet communications interface. The key benefits lie in the sensors' compactness and small dimensions, which allows them to be located anywhere within the production process, even if space is at a premium.

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Wine bottle inspection
Reh Kendermann, a major wine filling operation in Bingen am Rhein, is among the many companies that employ CLK vision solutions. It needed a system to examine several aspects of the wine bottle labeling process. The aim was to monitor not only the correct and exact positioning of the labels, but also certain printed parameters, such as the alcohol content, article number etc. 

It is essential that this data is printed correctly and is clearly legible. The new monitoring system was to be integrated in the existing filling system and achieve a maximum inspection speed of up to 10 bottles a second. In the past, high-speed applications such as this had generally been the preserve of PC-based image processing systems.

To meet this particular customer’s requirements, CLK selected the advanced In-Sight 4000 vision sensor. Taking into account the operating environment, infrared flash lighting was used. It’s high intensity and short bursts eliminate the risk of blur or image motion at such high production speeds. Another benefit of this type of lighting is that no screening from other light sources is required. 

The vision sensor also includes an I/O interface for automatically rejecting non-compliant bottles, and a remote maintenance option via the integrated Ethernet interface. In view of food industry hygiene requirements, the system was installed in a watertight IP67 stainless steel enclosure.

Immediately after the labels are applied, the bottles pass the vision sensor. Each image is analyzed and compared with the previously defined standard reference values. The software scans a specific area of the image for a particular pattern. Once it is detected, the software knows the positions of the other character sequences that are to be inspected. This advanced location finding ability enables the system to monitor the presence of the required data even if the position of the labels varies considerably. 

After the positioning check, the print quality and legibility are measured. The customer can set tolerance limits for categorizing the labels as Not OK (fail) or OK (pass). If a bottle is flagged as Not OK, the system sends a signal to the filling line's machine control, so that the relevant bottle can be automatically isolated. 

This new system eliminated the laborious and subjective manual monitoring which, because of the limits of human concentration, inevitably results in errors. By ensuring that all labels are both of good quality and legible, the system has achieved a reduction in production costs.

Article submitted by:
John Lewis, Cognex Corporation
Phone: (508) 650-3140