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Vision technology - meeting the challenge of food quality standards.

Vision Technology - Meeting the Challenge of Food Quality Standards

The second stage of the Food Safety Act was implemented on January 1st this year. It dealt not only with hygiene within the food industry but also with labelling and presentation of food products, reflecting the public's concern over food safety. Food companies are, therefore, obliged by law to take a close look at their quality assurance standards.

Such legislation is a direct result of cases involving product tampering, which have reached unprecedented levels in recent years. Reports on the major cause of food prosecutions indicate that the category 'foreign bodies' figures as the greatest cause of food contamination and accounts for more than half of all the prosecutions. Although prosecution cases concerned with glass in babyfood containers attract the greatest publicity, even food companies operating in less 'sensitive' areas are now faced with the enhanced powers of the enforcement agencies, that are contained in the Act. Thus, an increased risk of prosecutions arises if a company are unable to prove their ability to demonstrate 'due diligence'. Failure to detect contaminants and tamper-evident seals, or provide correct labelling within the manufacturing and packaging plant can therefore have a damaging effect on the company's business, not only in the form of increased fines but also in consumer perception of product quality.

Some companies already use a limited form of human inspection as part of their quality control operation. However, in some cases this has proved to be inadequate to meet the needs of modern manufacturing plants.

Research within one major UK food company reveals that human visual checks are only 30 percent effective. This may be accounted for by the human eye's tendency to tiredness over a normal working shift, while the speed of production lines is usually too fast for a total inspection to be achieved.

Added to this is the fact that this general percentage of effectiveness has a very large performance spread. Human inspection has the bonus of 'judgement' behind the eyes, however, whilst this judgement is taking place, many containers pass by uninspected.

On the other hand, a vision system can offer inspection of all containers with exactly the same degree of inspection applied to every container. The general feeling within the industry is therefore turning towards the idea that in-line, automated quality control testing should be regarded as an essential verification of good manufacturing practice.

Inex Vision Systems of Altrincham, Cheshire have been supplying quality inspection systems to the UK food industry for more than 30 years, mainly in the form of empty container inspection for the detection of defective and contaminated containers prior to filling. Many of these early inspectors used simple electronic scanning methods. However, to meet the new product quality assurance needs of the industry, Inex Vision Systems has developed a new type of machine vision system to provide the necessary quality control standards. This has proved possible with the introduction of fast computer processing and small, robust cameras that allow the inspection of new products and applications which, previously, had not been possible to inspect. Utilising multiple video cameras, a vision engine and advanced feature recognition technology, their P.I*Scan package inspection systems provides visual inspection at line speeds up to 1200 products a minute.

While inspecting products for overall quality and integrity, the system uses 'feature windows' and 'search lines' to analyze distinctive shapes, sizes and patterns within specific areas of the product. As the products pass at high speed through the inspection area, strobe lights instantaneously illuminate and visually 'freeze' each product, Simultaneously, high resolution cameras - electronic eyes - obtain an image of the product in milliseconds, the systems' computer analyzes the mosaic of digitised pixels, inspecting for specific parameters that the operator has preprogrammed.

Thus, inspection for any sort of product defect can be achieved. Typical applications include detection of:

* tamper-evident seals;

* incorrect size, shape or colour of the container;

* incorrect or missing batch and datecoding;

* incorrect or improperly positioned labelling;

* faulty closures;

* improper fill levels

This is to name but a few of the possible functions to inspect for overall quality and integrity of the packaged product.

Additionally, Inex has developed many special algorithms to carry out defined tasks within the feature windows to allow application-specific inspections.

All the above-mentioned features ensure that detection of packaging flaws takes place within the manufacturing facility. Faulty products, which would slip past the eyes of a human inspector, are rejected off the line before they turn up as defective or dangerous products on retail shelves or in customers' homes. Is this an unproven product with no installed base? Certainly not! One application of this system (the DairyScan) is currently operating in dairies throughout the country. This system uses the same vision technology to inspect the sidewall area of milk bottles as well as to provide post-filler checks on the finished product - a concept which had previously never been undertaken. The success achieved in the dairy industry has proved the flexibility of the system even within the arduous constraints of the bottling environment.

However, there is still a degree of scepticism about vision products, mainly due to the failure of many small vision companies, which have appeared and disappeared within a couple of years, leaving behind a base of installations with no provision for service or spare parts. However, with the introduction of P.I*Scan and its already well-proven background within the dairy industry, Inex Vision Systems hope to have restored customers' confidence in the benefits of vision technology.

As the new packages enter the market, and legislative seals and compulsory information, such as dates and lists of contents are imposed, a vision system with upgradability is essential. The P.I*Scan offers a base on which to build for future needs. Ultimately, management reporting of efficiencies can be incorporated by means of a Management Software Package. This would mean that defects are tracked throughout production, allowing flaws to be monitored, to allow their origin to be found and so increase efficiencies of operation. This statistical data output permits operators to respond to emerging problems, thus providing a practical solution to the need for a manufacturer to be in full control of his product.

In short, the P.I*Scan is a highly flexible system which is capable of performing numerous real-time visual inspection tasks to maintain product quality, heighten productivity, reduce waste - and increase profits. In the real-life environment of fast-moving packaged goods, quality sells - and poor quality costs. The P.I*Scan is a multi-purpose vision system to ensure that consistent product quality is never compromised.

Thus, the installation of such a vision system into manufacturing lines enures sound quality control standards of ALL the processed products, and is a major advancement in meeting the challenge of food safety and demonstrating 'due diligence'.
COPYRIGHT 1991 Food Trade Press Ltd.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Publication:Food Trade Review
Date:Apr 1, 1991
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