Inspection Technologies Keep Quality High in Packaging Systems

X-ray, metal detection and vision technologies keep the quality in your packaging systems.

By Judy Rice, Contributing Editor

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No matter how much time, money and imagination you put into formulating and marketing your products, failed packaging can obliterate all your best efforts. Stale, spoiled or contaminated product almost certainly spells disaster. Under-filled packaging, leakers, cracked or dented containers, improperly applied closures and out-of-position or misprinted labels all do their share to erode consumer confidence in your product.

Quality control on the packaging line is crucial and should never be underestimated.

Protecting the quality and safety of your packaged products is paramount to your marketing and financial success. Adjusting and expanding packaging options to meet consumer expectations are keys to maintaining or building your position in the marketplace.

So as food and beverage companies incorporate new packaging concepts, they need to continually re-evaluate how these changes affect quality control procedures and how best to optimize packaging QC results on a consistent, cost-efficient basis.

Iron checking for iron

Metal detectors have become a front-line defense in packaging quality control. With quantum leaps in sensitivity, they can now detect pieces of ferrous and non-ferrous metal much smaller than previous generations of the machines could. But they still cannot detect all metal. They also are handicapped by product or packaging that includes metal.

Typical metal detector applications in the food industry included bakery (everything from bulk ingredients to finished packaged products), dairy products (which get into the issue of wet products), meat and poultry processing (which require washdown products) and snack foods/bulk solids, according to Fortress Technology Inc. (, Scarborough, Ontario.

For instance, food processors who use bulk bags of ingredients such as flour, sugar or spices and seasonings need assurance that these ingredients are free of metal contaminants. Fortress' Phantom metal detection systems inspect 50-100 lb. bags, finding particles as small as 2 mm.

Metal detection systems need to be sited at the end of main production flow, which places them in or just ahead of the packaging department. Conveyor-based detectors must include the following, according to supplier Loma Systems Inc. (, Carol Stream, Ill., for the most efficient performance:
  • An automatic rejection system.
  • A lockable box to receive the rejected product.
  • A full enclosure between the search head and the rejection bin.
  • A device to confirm that the contaminated products have been successfully rejected into the bin.
  • An automatic belt stop failsafe system, to activate if there is air pressure failure, a detector fault, failure of the reject system or when the reject product collection bin is full.
Pipeline systems must include an audible and visual indication of rejection, and free fall systems require the facility to produce a double pack, if an automatic reject system is not possible.

X-rays peer inside

X-ray systems are becoming a common feature of food processing plants throughout the world. X-ray inspection has a few advantages over metal detection and checkweighing systems. In addition to snagging metals, even when faced with metallic packaging, X-ray systems find calcified bone, glass, PVC, TFE and other plastics, stone, ceramic, cement and rubber. They also help identify clumps of ingredients, missing items and malformed or broken products.

Super Store Industries, a Stockton, Calif.-based captive food processing operation owned by two grocery chains, operates dairy plants in Turlock and Fairfield, Calif., as well as a dry and frozen food distribution center in Lathrop. The company decided to add foil membrane lidding as a tamper-evident/freshness-protecting enhancement for its plastic 6-oz. and 8-oz. yogurt cups before the plastic overcaps are applied. But the conversion required a reassessment of quality control procedures.

Super Store had been using metal detection systems to inspect the filled/sealed yogurt cups. But the change to foil lidding required a move away from metal detectors. "So we budgeted for new inspection equipment," says Yancy Hopper, chief engineer.

After evaluating options, Super Store chose the ScanTrac 200 X-ray system supplied by InspX (, a Fremont, Calif., joint venture between Key Technology Inc., Walla Walla, Wash., and Peco Controls Corp., Fremont, Calif. The unit provides inspection beyond metal contamination detection. Using low-energy X-ray and image processing software, it also detects glass shards, stones, bones, rubber and other dense foreign materials. In addition, it detects product voids and underfillls and damaged or out-of-spec containers.

The change was worth it. "Going to foil seals and then placing plastic lids on the cups gave us tamper-resistant packaging as well as an air tight cover over the yogurt—with all this done on the same line," Hopper continues. "We were able to eliminate the shrink film neck banding equipment that was in place in the packaging area to apply tamper-evident bands around the overcapped cups."

The processor also was able to eliminate the high-speed weigh scales that previously were used to ferret out yogurt underfills. The quality assurance lab personnel, however, still do periodic checks of the finished product as an added safeguard to ensure proper fills.

Super Store dairy plants produce plain, pre-stirred and fruit-on-the-bottom yogurt varieties. Notes Hopper, "The X-ray system has no problem with fruit or yogurt densities. We only have to set up for size changes. Our product sizes are programmed into the system. So it is as simple as selecting the size on the operator screen and adjusting one guide rail to product width, and we're ready to run."

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