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Loma Cintex discusses metal detection for food inspection.

Food-inspection systems play a fundamental role in assisting food manufacturers with the issues of safety, time and cost.

However, with consumer demand for an increasingly varied diet and constantly changing eating habits, food manufacturers have been forced to increase their range of food products to maximise profits and increase consumer satisfaction.

This has led to the need for food-inspection systems that are capable of adapting to different products, packages and sizes.

This change in production trend has presented a complicated challenge for food manufacturers; how to decide what operating frequency to set their metal detectors at in order to achieve the optimum levels of sensitivity for every product they handle.

This is made particularly complicated by ‘Product Effect’ – a signal that electrically conductive products give to the metal detector, which are interpreted by the system as non-magnetic metal.

If the product signal is large it can overwhelm the metal-detector electronics and make compensating for the effect difficult, potentially degrading metal-detector performance.

The higher the frequency, the higher the product effect and, to complicate matters further, the signal from non-magnetic metals improves as frequency increases.

To achieve optimum non-magnetic metal sensitivity, producers set their machines at a higher operating frequency.

However, this higher frequency increases product effect and determining a common ground is not always easy.

The level of signal will be influenced by material type, electronic conductivity size and how these items interact within the detectors field.

Until now, the most technically advanced solution has been ‘Multi Frequency’ models of metal detection, which allow the operator to choose two or three preset frequencies for a small number of different products.

However, the current systems force the producer to estimate a suitable, compromised frequency for a multitude of products that is not always satisfactory, meaning the sensitivity levels of metal detection for any one product can never be optimum.

This can lead to a compromise on sensitivity or false rejects – both of which have serious repercussions for the producer.

If the operator needs to make a change to the frequency, this would currently mean downtime for the machine as the process is complicated, time consuming and costly.

Loma Systems has introduced its Variable Frequency IQ3+ Metal Detectors, which allow for virtually any frequency across a 31 to 882kHZ range.

The system can be configured so the metal detector automatically picks the frequency for each product during the product ‘learn’ or ‘calibration’ and has significant data space to store the frequency details of up to 200 different products.

This simplifies the operation of the detector from the user’s perspective, with the benefit of low product wastage or recall costs.

Variable frequency also allows for greater flexibility in aperture sizing and enables Loma to stock metal detectors for quick delivery.

This technology has many benefits for food manufacturers.

Prior to Variable Frequency, various parts used in the manufacture and maintenance of metal detectors required a large spare-parts inventory, which can be expensive for both parties, as well as impractical for customers.

All Loma IQ3+ Metal Detectors, regardless of size, style or frequency, use a common set of parts, making the process efficient and convenient for all customers.

Variable Frequency allows for an increased flexibility in the use and location of the metal detector.

When multiple products are considered, the ability to define an optimum frequency for each product instead of a single frequency offers greater flexibility and security.

Investing in a Loma IQ3+ variable-frequency metal detector allows food manufacturers to futureproof their inspection systems, according to the company.

While there are still a number of process lines running with a single product, this is becoming rare and the demand for the ability to run multiple products at their optimum sensitivity levels on the same line is becoming greater – thus the need for variable-frequency systems is increasing.

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