Food Safety / Process and Operations / Inspection and Sorting

Inspection Systems Now Faster, Cheaper And More Versatile

Machine vision breakthroughs are ushering in a new generation of food inspection systems that do more for less than previous solutions.

By Kevin T. Higgins, Managing Editor

Earlier and more frequent detection of product defects is becoming more common with inspection systems that are faster, cheaper and more versatile than was possible even a few years ago.

In the case of the V6300 vision inspection system, add multi-tasking to the list of benefits. A handful of the high-speed systems from the CI-Vision unit of Mettler-Toledo already are validated and running in food facilities. Some spotlight at this month's Pack Expo Las Vegas show should kick start a broader rollout, believes Stephen Dryer, product manager at the Aurora, Ill.-based division.

The V6300 supports up to five cameras for multiple quality checks by a single processor — label positioning, fill level, bar code verification, alphanumeric codes and other inspections. It's all possible "as long as we have a large enough field of view," says Dryer. Coupled with the firm's CIVCore software, data crunching can match line speeds of 1,000 units a minute, with a much higher theoretical maximum speed.

Instead of smart cameras, the system relies on GigE cameras with telecentric lenses that receive light in straight lines, overcoming the image-size distortions that can disrupt inspection results when light is received in a cone configuration. They also give CI-Vision the ability to update the chip sets as newer generations are introduced.

Ethernet cables connect the cameras to the central processing unit, where the software analyzes high-resolution images and stores those of out-of-spec product. The system can be programmed to send a line-shutdown notice after a predetermined number of product failures. Users can purchase a kit with all the components or order a modular frame for faster start-up, cutting the frame bars to fit the line and then mounting the cameras for overhead and side views. Once the system is trained on the pass/fail distinction for a variable, the information is stored for later push-button changeover.

Dryer describes the V6300 as "the latest and greatest" automated machine inspection system from the firm, which was founded 30 years ago by a U.S. Air Force veteran with a background in military machine vision. Doing business as Conversions Inc., the organization functioned as a system integrator until it developed proprietary software and paired it with best-in-class components for turnkey solutions. The firm was acquired by Mettler-Toledo three years ago, increasing its focus on food & beverage applications.

Starter X-ray set

Biological and chemical contamination events are headline grabbers in product recalls, "but the vast majority of recalls are for foreign objects," points out Bob Ries, lead product manager-product inspection at Thermo Fisher Scientific Inc., Minneapolis. Metal detectors continue to be the go-to option for most food companies to lower the likelihood of those recalls, but X-ray inspection is rapidly gaining ground, and momentum is building with Thermo Fisher's new entry-level unit that combines superior performance with a more easily rationalized price point.

Dubbed the NextGuard, the new machine provides considerably greater detection sensitivity than Thermo Fisher's EZx unit, which is being phased out. Unlike the EZx, NextGuard retains images of inspected product, providing an audit trail for compliance with tighter regulatory requirements and customer demands.

Plastic remains a detection challenge, but glass, stone and both ferrous and nonferrous metals are readily identified, he says. Simplified setup and operation address other concerns, particularly among new converts to X-ray inspection who lack in-house technical expertise.

False positives continue to be an issue with both metal detectors and X-ray, but because the new system retains the images of suspicious products, "you can quickly figure out if there was an actual contaminant or if it was a false positive," notes Ries. "It's very hard to analyze metal detector rejects."

Thermo's first foray into X-ray came in 1984 with a system known as an image intensifier. "It was the size of a small car," he laughs, and the technical support necessary to operate it added to its high initial cost.

With performance improving and prices declining, more food companies are embracing the technology. Ries cites the example of a Chinese ice cream manufacturer that replaced metal detectors, which perform poorly with conductive materials like frozen liquids, with multiple X-rays. Thermo's X-ray sales volume has climbed to half that of metal detectors, and with double-digit volume increases continuing, X-ray will become the firm's dominant end-of-line detection solution in the foreseeable future, he predicts.

Even plastic can be identified with chemical imaging technology (CIT), its developers claim, but the capabilities extend beyond ejection of foreign materials. Chemical imaging renders a full spectral analysis of the food itself, giving users the ability to detect product defects early in the process, thereby separating substandard raw materials before value is added by downstream processes.

Two Austrian firms, EVK Di Kerschhaggl and Insort, have licensed chemical imaging for fruits, nuts and other applications. Exclusive rights for potato inspection recently were given to Key Technology Inc. The Walla Walla, Wash., machine builder will apply the advanced machine vision in several of its sortation and defect-removal systems. Color defects, peel residue, sugar ends and even Erwina bacteria can be flagged, according to Insort.

CIT measures 316 spectral wavelengths within a plain measured in nanometers. Hyperspectral sensors layer measurements of the target's chemical composition, according to John Kadinger, marketing manager at Key. While bench-scale chemical imaging systems have been available for 20 years, availability in industrial hardened machines capable of high-volume throughput is a new breakthrough, he says. CIT complements the BioPrint system Key acquired earlier this year when it purchased the Belgian firm Visys.

Sensors and software are a big part of the advanced capabilities of CIT, just as they play a role in improved X-ray machines and in-line inspection systems. But, as with improvements in most automation technology, a big debt is owed to Gordon Moore's Law, says Kadinger, referencing the cofounder of Intel. Almost 50 years have passed since Mr. Moore observed that the speed and memory of computer chips doubled every two years, and the trend was likely to continue. His prediction has been validated in many technical applications, including advances in food inspection systems.