Jack Mans, Plant Operations Editor
In the state of Texas, a tax stamp must be applied to each liquor bottle sold at the wholesale level, such as to hotels and restaurants. For Dallas-based Goody-Goody Liquors Inc., this was a major challenge. Goody Goody Liquors is the number one volume retail store chain, and its wholesale division services more than 600 hotels and restaurants in the Dallas area.
Goody Goody processes 60 botles/min, and the bottles have different shapes and the labels have different backgrounds. In addition, the label position varies and the lighting continually changes. The company wanted to automate the process of reading and applying the stamps to ensure that each bottle had a tax stamp and to store the tax stamp number in a database with the bottle number for audit purposes.
To meet this bar code reading challenge, Goody Goody management began talking to Cisco-Eagle Inc., because of its experience in, as the company puts it, "Getting the right amount of the right material to the right place at the right time in the right sequence at the right position in the right condition for the right cost in a safe manner."
Cisco-Eagle provides solutions for the movement, storage, retrieval, control and protection of materials and products throughout their manufacture, distribution, consumption and disposal.
The first automated system that Cisco-Eagle supplied didn't meet Goody Goody's stringent requirements because of problems with a number of different bar code readers. One reader was only able to read the bar code against the widely varying bottle backgrounds about 95 percent of the time. This resulted in a failure to read about every 20 seconds, which negated the main benefits of automation.
Another bar code reader had difficulty integrating with the Rockwell Automation ControlLogix PLC controlling the bottling line. Cisco-Eagle received little direct help from the manufacturer of the bar code reader to resolve this critical issue.
Next, Cisco-Eagle tried the DataMan 500 bar code reader from Cognex Machine Vision Systems and discovered it rarely was unable to read a bar code. Sam Chen, senior robotics and software engineer for Cisco-Eagle, says, "Cognex customer support is remarkable. They worked with us continuously to make this application a success."
Cisco-Eagle worked with Goody Goody Liquor to develop a system that automatically applies the tax stamps, which have linear bar codes, and reads the bar codes for verification and tracking. The liquor bottles are conveyed through the system.
A labeler automatically applies the stamp, but the system must be able to handle situations where the applicator fails. Machine vision is required to identify bottles that do not have a stamp on them, so they can be removed from the line. The image-based reader also captures the tax stamp number so it can be entered into a database along with the bottle number in case of an audit.
Chen says, "We have tried various machine vision systems in the past for this application, but have experienced reliability problems. One of the challenges is that the labels pass by the bar code reader very quickly.
"The bottles themselves are different with some being round and others being rectangular, which affects the way the bar codes are presented. The line processes many different liquor bottles, many of which provide a background that can be difficult to read against, such as very dark, very bright or striped packaging; and opaque or transparent liquid content. Finally, the line is used in a warehouse where the lighting is shifting constantly as lights are turned on and off and the degree of natural lighting changes with the time of day and weather."
Selection of bar code reader
Chen says, "We decided to go with the Cognex DataMan 500 bar code reader because it has a larger depth of field, higher resolution and decoding technology that made it possible to reliably read the bar codes in spite of the challenges of this application."
According to Cognex, DataMan 500 is the first reader for the logistics industry to use liquid lens autofocus technology that maximizes the depth of field for greater reliability in applications where package position varies.
DataMan 500 offers 1024 x 768 image resolution and also offers advanced decoding that makes it possible to easily read badly printed codes, damaged codes, distorted codes, codes on a noisy background, extreme perspective, codes with low height, blurred codes, scratched codes and more.
Chen says, "The other bar code reader manufacturers gave us their manuals and technical support numbers, and we had to figure out how to apply and integrate the new products largely on our own. On the other hand, Cognex taught us step by step how to use the product and helped us integrate their bar code reader into our system. When we had problems, they came and worked with us until the application was successful."
Integrate reader and labeler
The Cognex bar code reader is configured by connecting it to a personal computer. A graphic user interface is used to set parameters such as aperture, gain and focus communications parameters.
The DataMan 500 communicates using Rockwell's EtherNet/IP protocol and has a driver for Rockwell PLCs that simplifies the integration task. Once the driver is installed in the PLC, the bar code reader shows up as a component. The PLC can then be easily programmed to issue commands to the reader with minimal programming.
In this application, the commands include: capture an image, provide feedback on whether or not a bar code was detected and send the bar code number. All of this was accomplished with only three lines of code.
Just before the bottles are put on the conveyor, an operator uses a hand scanner that reads the bar code on the label automatically and enters the number into a database.
The operator then places the bottle on the line, where a photoelectric sensor detects the bottle as it begins to move. The line runs at varying speeds, and the PLC tracks the position of each bottle by tallying the encoder pulses it has detected from when the bottle passed the first photo sensor.
As the bottle moves down the line, a pressure-sensitive labeler from Southern California Packaging Systems applies the tax stamp. Texas Labeling & Coding, the labeler distributor, worked with Goody Goody Liquors on the installation and startup of the labeler, as well as providing follow-up services.
Another photo sensor is mounted on the line just before the bar code reader and provides a signal to the PLC every time a bottle passes by on the conveyor. The PLC sends a signal to the bar code reader to begin capturing images, which it continues until it finds and reads a bar code. Based on the time and travel that has elapsed since the bottle was loaded on the line, the PLC knows which particular bottle was read by the bar code reader and stores the tax stamp bar code in the same database row as it had previously stored the label ID.
If the DataMan 500 cannot find a code, it sends a signal to the PLC, which triggers a reject mechanism to remove the bottle from the line at a downstream station.
Chen says, "The reliability of the Cognex bar code reader is substantially higher than the other bar code readers we tried in this application. It rarely fails to detect the label, even on bottles with the most confusing backgrounds and difficult lighting conditions.
"The bar code reader played a major role in the success of this application, which saves a huge amount of time that was previously spent applying labels, manually scanning labels and inputting the tax stamp information. The customer is very happy with the performance of the system, and we have not received a single service call on the bar code reader."
Cisco-Eagle Inc., 888-877-3861. www.cisco-eagle.com
Cognex Machine Vision Systems, 508-650-3000. www.cognex.com
Rockwell Automation, 414-382-2000. www.rockwellautomation.com
Southern California Packaging Systems, 909-598-3198. www.scpe.com
Texas Labeling & Coding, 817-377-1835. www.texaslabeling.com