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!