END OF LINE, INSPECTION & METAL DETECTION
Choose the metal detector that’s right for you
Heat and Control Africa’s GM Jeff Rossouw discusses the many factors to consider when evaluating metal detector inspection technology to help choose the best solution for your requirements.
P
rotecting your brand in the
vary in temperature. A metal detector
marketplace is one of the most
that uses multiple frequencies is more
important functions that a food
suitable for these applications. The most
manufacturer performs, but your
sophisticated metal detectors on the
investment in product quality could be
market use multi-spectrum technology.
lost with just one safety recall. Developing
Instead of relying on just one frequency,
and maintaining an effective, verifiable
a spectrum of multiple frequencies works
inspection programme is no longer an
simultaneously to filter out product signals,
option for processors; if in fact, it ever was.
a much more effective method than a
So, how can you protect your customers and your brand within your budget? Metal
single frequency. It also greatly reduces the number of false alarms.
detection is an effective and relatively and other commercial considerations are
AUTO-CALIBRATION AND AUTOLEARN ADVANTAGES
important, technical performance must
The metal detector that successfully
be the primary factor when evaluating
becomes a part of a plant quality control
a metal detector to trust with your
programme provides good sensitivity
brand’s reputation.
performance and is easy to set up and
inexpensive solution. While price, delivery
use, while providing a low level of false
PRODUCT EFFECT
rejects. Most metal detectors currently on
This is an important factor when selecting
the market perform self-checks to verify
a metal detector. If your products are
that the unit is in balance and performing
conductive (usually due to water, salt
properly. The auto-learn routine allows
or iron content), they will affect the
the user to acquire the characteristics
electromagnetic field of the metal detector,
of the product in the unit so that the
causing it to produce a false reject. Dry or
product can be inspected. An efficient
neutral products generally do not cause
auto-learn gives the best sensitivity, the
this effect. If product effect is a factor,
least number of false rejects and requires
select the correct frequency to move the
minimal manual adjustments. This gets
product effect signal away from the signal
the unit into production with a new product
of the contaminants. A metal detector
the quickest.
that uses a single frequency cannot making it unsuitable for inspecting a
SENSITIVITY AND COMMUNICATION
variety of product types or those that may
Metal detection sensitivity often depends
accommodate much signal variation,
THE MD’S CHECKLIST Consider these factors to determine the best metal detector for your needs: • Primary detection function: food or equipment safety or both? • Products characteristics for inspection • Size of particles to be detected • Sensitivity target for each metal type • Wet or dry inspection area • Temperature variations in the product or inspection area • Washdown: high or low pressure, caustic agents • Equipment integration with other equipment or the plant’s data network. on the operation. For example, if a metal detector’s primary function is to protect a key piece of equipment, such as a sheeter or slicer, the goal would be to eliminate metal that is large enough to damage the equipment. In another part of the line, a different level of sensitivity would be required to inspect a bulk flow of product. As final package inspection is usually the most demanding, a higher sensitivity would be needed to protect your product before reaching the marketplace. Your plant’s quality control group should have specific sensitivity targets for ferrous, nonferrous and stainless steel (even difficult to detect type 316) contaminants for each inspection operation. These targets should be communicated to the metal detector manufacturer so that they can select the appropriate equipment for
Product effect is an important factor when selecting a metal detector
each application. Remember to be flexible to achieve realistic and achievable goals within your budget.
ENVIRONMENTAL CONSIDERATIONS Start by evaluating your inspection area. Is it wet or dry? How much does the temperature vary? Selecting a metal detector suited for your operating environment is critical. One of the most common causes of metal detector failure is water intrusion into the electrical components. If there is a washdown
38
July 2021 | FOOD RE VIEW
