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Seminar on Metal Detectors in Food Industry
Presented by:- Aman Paul (10MTFTFC005)
Presented to:-SHIATS Seminar Committee
Introduction With the arrival of new era of food
technology, food safety has become bottleneck of very food industry.
Food Safety PieISO 22000
HACCPGMP
Soul of Food Safety
Underlining Food
Hazards
Reducing to Acceptable
Level
Checking Further
Contamination
Physical Biological
Chemical
Food Hazards
Food Safet
y
Metal Contaminants
Sources of Metal
Contamination
Raw Material Transpotation PackagingProcessingTransportation PackagingProcessing PackagingProcessingTransportation Packaging
Need of Metal Detection
1. Social Responsibility2. Consumer safety3. Firm’s Image
Basic Principle of Metal Detector
Faraday’s Law of EMI
Unit of emf = Volts
Φ = B.A.cosϴ
Construction & Working
Signal Generatio
n
Comparison with
Threshold
Alarm if Signal
>Threshold
Display Signals
Schematic Diagram
Factors Affecting Working of Metal
Detector Contaminant factors Product factors Installation factors Electronics factors Detector factors
Contaminant Factors Material properties
a) Magnetic permeability
b) Electrical conductivityGood
Conductors( σ)
Bad Conductors( σ)
Silver
Copper
Gold
Aluminium
Zinc
Nickel
Tin
Chromium
Lead
Mercury
More Dominant one
Conductivity stick
Ease of Detection Matrix
Size and Shape
a. Spherical objects are not detected easily in comparison to cylindrical ones.
b. Long objects are detected more easily.
Detector Factors
Orientation Effect
Easy for non-ferrous Difficult for ferrous
Easy for ferrousDifficult for non-ferrous
Position Effect
At centre magnetic field is weak and objects are difficult to detect
At sides the magnetic field is the strongest and easily detected
Aperture Size
Aperture Size
Lower the aperture size, higher is the sensitivity of
metal detector
Head Frequency
Higher the Frequency
, Higher the
Sensitivity
Lower the Frequency
, Lower the
Sensitivity
Detects Stainle
ss Steel
High Rates
of False Rejecti
ons
Installation Factors
Metal Free Zones MFZ 1For non
moving particle
s
MFZ 2For
moving particle
s
Vibrations Clearance EM/RF Interferences
Another Detector
(AM Receiver)
Motors, Clutch/Br
ake & Power Cables
Fluorescent Lamp
Mobile Phone
and Walkie Talkie
Air-Borne Disturbances in
Environment
EM/RF Interferenc
e
Product Factors
Moisture Recipe
Electronic Factors
Threshold Signal Processing Calibration
Alignment of Metal Detector-FSMS plan
The online testing of metal detectors should be carried out in the following manner:-
1. Hazard- Metal Particles
2. Location- All filing lines
3. Specification- Correct functioning of metal detection system and should detect operating limit defined by the factory. Critical Limit is SS 2.0mm.
Note- The test piece should be spherical and certified by the supplier for both operational and critical limits.
CCP monitoring procedure:-
Check proper functioning of metal detector at least once per shift with standard spherical test pieces of operational limit.
Ensure that the product incriminated by the metal detector is kept separately and sorted by offline metal detectors.
Metal retrieved from the rejections are retained and root cause analysis is done.
Record for online testing, offline testing and retrieved metal pieces.
In case of increasing number of metal retrievance proper correcting action should be taken by the production/engineering section .
Action in Case of Deviation
Incase the metal detector fails in the routine check, than stop the line.
Check the detector with 2mm SS, if it passes than release the product since last check and recalibrate the detector.
If detectors fails with 2mm SS, block the product since last check.
Pass the product through offline metal detector. Incinerate the rejections and rework the unrejected
ones.
Limitations
Sensitivity
Can only detect metal
contaminants
Metal diameter should be greater
than 1mm
Installation
Needs a bigger vertical space
Performance is affected
by noise and
vibrations
Thank you!
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