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Technical
Information
Detectamet Metal
Detectable Material
For some time, E-Components & Chains
Limited have sold a range of tools
in a metal detectable plastic. This
is polypropylene with a carefully
formulated additive and the finished
articles have been approved for
direct food contact under EU90/128.
We have recently introduced red,
green and yellow colours in addition
to the standard blue.
One of the most common technical
enquiries that we have received
regarding our metal detectable
products is, “How much of your
material is detectable?”
The answer to this question is not
as straightforward as it might first
appear. Every food manufacturing
plant has a metal detector
calibrated in a different way and
set at varying levels of intensity.
The type of matter going through the
detector (particularly whether wet
or dry), its size, speed and
orientation also have an effect.
However, it is standard practice to
calibrate detectors using ferrous
ball bearings of known diameter.
Therefore, ECC have produced a set
of detectable plastic spheres and
cubes of varying sizes to aid in
calibrating machines and
understanding the answer to the
above question.
The following sizes are available as
a set, as illustrated: 8mm cube, 6mm
cube, 4mm cube, 2mm cube, 20x10x2mm
plaque, 3mm sphere, 6mm sphere, 10mm
sphere.
We carried out tests using these
shapes on 24th February 2005 to find
approximate equivalent ferrous
calibrations. Two states were
simulated: wet and dry. The minimum
machine settings were used in each
case where the detectable shapes
achieved detection. Ferrous ball
bearings were then passed through
until the smallest was found that
achieved the same reading on the
detector. The following results were
obtained.
Approximate Calibration Settings for
ECC Detectamet Metal Detectable
Material
Machine: Safeline Signature IS
Settings: 300kHz frequency, 0o phase
(typical dry material setting)
Shape Size (Approximate mass of
plastic) Approximate Equivalent
Ferrous Machine Sensitivity
Cube 8mm (0.52g) 1.5mm Fe 109
6mm (0.22g) 1.2mm Fe 139
4mm (0.06g) 0.8mm Fe 199
2mm (0.01g) Not detected 199
Sphere 10mm (0.53g) 1.5mm Fe 109
6mm (0.11g) 1.0mm Fe 149
3mm (0.01g) Not detected 199
Machine: Safeline Signature IS
Settings: 25kHz frequency, 90o phase
(typical wet material setting)
Shape Size Approximate Equivalent
Ferrous Machine Sensitivity
Cube 8mm (0.52g) 3.5mm Fe 0
6mm (0.22g) 2.5mm Fe 30
4mm (0.06g) 1.8mm Fe 70
2mm (0.01g) 0.8mm Fe 170
Sphere 10mm (0.53g) 3.5mm Fe 0
6mm (0.11g) 2.2mm Fe 40
3mm (0.01g) 1.0mm Fe 150
The same results were obtained
irrespective of the material’s
colour.
These results imply the following,
for example.
If a factory runs an in-line metal
detector for a dry food product,
such as biscuits, set at 300kHz at
0o and sensitive enough that a 0.8mm
diameter ferrous ball bearing will
trigger an alarm, then a 4mm cube
(or 0.06g) of Detectamet metal
detectable plastic may be needed to
set off the alarm.
Another factory running a similar
detection system set for a wet
product, such as a microwave meal,
set at 25kHz at 90o and sensitive
enough that a 0.8mm ferrous ball
bearing will trigger an alarm,
should detect a 2mm cube (or 0.01g)
of material.
However, since every plant uses
different machines at different
settings, we recommend that quality
control staff carry out their own
calibration tests to ascertain their
own requirements. The metal
detectable test shapes described
above are available now from
E-Components & Chains Ltd for this
purpose. Please call us now to
obtain your calibration set. |
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