Volume 17 | Number 1 | Spring 2005 | Automation Issue

Researchers Tackle Challenge of Automatically Inspecting Package Integrity

Joe Ramirez of Cryovac and Georgia Tech researcher Colin Usher run a test on the package inspection cell.

Although automation technology is commonplace in all food processing plants, visual screening tasks, such as package inspection, remain a manual function performed by line workers. With the growing use of integrated packaging technology combined with a growing interest in ensuring the safety of food products through the distribution chain, improved screening accuracy and automation is needed by poultry, meat, and vegetable processors. Georgia Tech researchers are tackling this challenge with the design of an automated package inspection system.

“Package integrity has taken on increased concern both from a tampering and food safety standpoint as well as for the rapid detection of flaws for real-time process control and monitoring. Automated systems would function to assist in controlling the process and help to minimize the potential impact due to rework,” explains Wayne Daley, research engineer.

Daley and a team of researchers have been working with Cryovac, Inc., a leading manufacturer of film and packaging material for the food industry, to develop an integrated solution that combines the knowledge of packaging materials and their properties with imaging and other sensing systems. Together they have designed and tested a prototype system that automatically inspects packages as they exit a heat-sealing machine.

Using visible imaging to find defective seals has proven to be a difficult task, explains Colin Usher, research scientist. Different color packages as well as the clear properties of the film itself led to difficulty in using a conventional vision system for reliable identification of film tears and other defects. The research team addressed this challenge by developing a proprietary approach that modifies the properties of the film so that special imaging techniques can be used to identify defective package seals.

The current prototype system covers both the top and bottom of a conveyor belt, creating an inspection “tunnel.” In the center of the system, where the inspection process takes place, there is a separation in the conveyor belt. As a package passes over this separation, it is imaged so that the seal on both sides and the bottom of the package is inspected. In addition to inspecting the seal integrity, a camera located above the packages looks for proper label placement.

The inspection cell is designed to process packages output from multiple packaging machines via a conveyor belt feed. Each packaging system will sit inline with a belt that redirects packages to and through the inspection cell. The packages are inspected, and the ones with defective seals or improperly placed labels will be automatically rejected via a reject mechanism. These packages will then be dumped into a rework bin where they can be separated and repackaged.

The team is now completing development and testing of a laboratory version of the system, and recently received funding from Georgia’s Traditional Industries Program for Food Processing to conduct field trials of the system in an actual plant setting. “A field trial of the system operating in a production environment would serve to demonstrate the system operating under real-world conditions and enhance the potential for commercialization,” says Usher. “Our plan is to install the system in a production packaging facility and let it run for a reasonable period of time to evaluate the robustness of the hardware design as well as the accuracy of the vision inspection algorithms. The end result of such testing should yield a fully capable system ready for commercialization.”

Usher says the benefits of such an inspection system are numerous. Because of high labor requirements, it is virtually impossible for a plant to thoroughly inspect all of the packaged product leaving its facility for seal integrity. An automated inspection system would allow the plant to verify 100% of the product that is to be delivered. It will also allow the plant to maintain visual records of defects found to help identify possible ways of further reducing their occurrence. More importantly, such a system working in conjunction with the wrapping machine can provide instant feedback on system settings that might be impacting subtle changes in package seal integrity. Improperly packaged product not only causes leaks and messes on display shelves, but it also allows food products to spoil faster. Consequently, the manufacturing assurance of packaging seal integrity improves the confidence of retailers and distributors that shelf life projections will be met.