On-Line Inspection System Produces 99% Satisfaction

Ruth A. Mendonsa

The thought of inspecting a million cans of food a day -- almost 700 cans per minute -- is daunting even with the advantages of today's high-speed automation. And when you add to the job a goal of 99 percent overall product quality and production efficiency, the task might seem impossible. But at H.J. Heinz's food production and packaging operation in London, these were the expectations.
Heinz's employees process in excess of one million 8-oz cans of food per day through just two of its high-speed automated lines in three shifts over 24 hours. But the company was experiencing significant difficulties reaching its quality and efficiency goals -- what it calls "99 percent customer service." Improperly formed cans or cans with damaged flanges were too often passing by human inspectors and catching in the rails of the conveyance system, stopping up the line and requiring the operator to locate and correct the problem. Damaged flanges could also cause major incidents in the sterilization process, resulting in extended downtime and additional costs in materials and labor.
Heinz's canning manager, Norman McManus, turned to MK Inspection Services (MKIS) of Leighton Buzzard, UK, to provide a solution. The director of MKIS selected the SmartImage Sensor System from DVT Corp. in Norcross, Ga., for its ease of installation and price performance. MKIS integrated the system on the line, which included installing proper lighting, control panels and rejection devices.
The system performs a visual inspection of each can as it passes under a sensor head that contains a CCD array. The SmartImage Sensor captures the image using a photoelectric cell from Omron Electronics of Schaumburg, Ill., to trigger its timing. Using DVT's patented technology, the image is transferred directly to the RAM of the system's stand-alone processor. DVT Corp.'s proprietary Windows-based FrameWork firmware then analyzes the image with SoftSensor inspection tools.
In this application, the metallic surface required a powerful, even lighting source. LED ring lighting with a diffusion hood provided proper illumination for inspection. A simple air jet rejection device from TapTone Container Inspection Systems in North Falmouth, Mass., was installed, and a portion of the conveyor's railing was removed to blow the bad cans into a reject bin beside the line. MKIS also developed and installed an LCD control panel with a function display.
This orchestra of photonic devices worked in concert to provide a perfect solution for the canning company. Since the system's installation, the line has been running consistently at 99 percent customer service or better, said Heinz's McManus. He estimates the payback period for the inspection system to be less than four months.