Metal Detection The Basics

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Metal Detection - The Basics
North America Fortress Technology Inc. Toronto,
Canada Phone [phone] Fax (416)
754-2976 Email fortress_at_fortresstechnology.com
Europe Fortress Technology (Europe)
Ltd. Banbury, UK Phone [phone] Fax
44 (0) 1295 265277 Email europe_at_fortresstech
nology.com
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Contents
1. Metal Detection - The Basic Principles
1.1 Theory of Operation 1.2 Product
Effect and Phasing 1.3 Metal Free Area
1.4 Sensitivity 1.5 Types of Metal
1.6 Shapes and Orientation 2. Testing
2.1 Test Sample 2.2 Frequency 2.3
Procedure 2.4 Records 3. Sources of
Interference 4. Applications 4.1
Conveyor (End of Line) 4.2 Gravity
4.2 Pipeline 5. Good Practice Guidelines
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Balanced Coil
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Balanced Coil
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Product Effect
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Phasing
Resistive (Conductive) R
Stainless Steel (1 mm) I.e 304. 316
Non Ferrous (1 mm) I.e. Copper, Brass, Ali.
Ferrous (1 mm) I.e. Iron Steel
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Reactive (Magnetic) x
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Phasing With Product
Resistive (Conductive) R
Conductive/ Wet Product (meat, cheese, moist
bread)
Stainless Steel (1 mm) I.e. 304. 316
Non Ferrous (1 mm) I.e. Copper, Brass, Ali
Ferrous (1 mm) I.e. Iron, Steel
Reactive (Magnetic) x
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Metal Free Area
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Sensitivity
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Types of Metal
2.0mm Fe
2.0mm Fe
2.0mm Non Fe
3.0mm Non Fe
4.0mm SS
3.0mm SS
Dry Product Mode
Wet Product Mode
(Example of Ratios ONLY)
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Shapes Orientation of Metal

• Ferrous Wires
• A - Easiest position, biggest signal.
• B, C - Hardest Position, smallest signal.
• Non-Ferrous and Stainless Steel Wires
• B, C - Easiest position, biggest signal.
• A - Hardest position, smallest signal.

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Typical Guidelines for Sensitivity
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Detector Performance

• Isolated Rollers - prevent loops
• High Quality Belt - Metal Free, Carbon Free,
  Interlocked finger
• Splice, or Plastic Modular Belt (White or
  Natural)
• Low vibration and Static
• Adequate metal free area

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Typical Metal Detector Conveyor Reject Reject
Options
Diverter
Pusher
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Drop Through / Gravity Metal Detector
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Drop Through / Gravity Metal Detector

• A drop through / gravity detection system is
  ideally suited to inspecting dry, free flowing
  products such as
• Grains, flours, cereals
• Rice, nuts, sugar
• Plastic pellets and flakes
• The following critical factors must be known when
  designing a
• successful drop through / gravity detection
  system
• Flow rate
• Bulk density
• Free fall distance
• Pipe size
• Space available
• Testing procedure (insert recovery)

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Pipe System
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Pipeline Metal Detector

• A pipeline inspection system is ideally suited to
  inspecting liquid,
• slurries or paste products that can be pumped
  through.
• Typical pipe products would include
• Sauces
• Dairy products
• Meat slurries
• Juices etc.
• The following critical factors must be known when
  designing a
• successful pipeline detection system
• Pipe I.D.
• Pipe clamp connection style (tri-clamp, I-line
  etc)
• Product flow rate (GMP)
• Product viscosity
• Product temperature range
• Product pressure
• Expected cleanup procedures (wash down, pipe
  pig, etc.)

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Metal Detection System Sensitivity QA Test Form
Location Date Time Samples Used Results (signals
) Corrective Action
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Good Practice
1. Prevention 1.1 Training 1.2
Controlled Maintenance 1.3 Regular
Inspection Good Housekeeping 2.
Sensitivity 2.1 Identify Standards for
products (maximise sensitivity) 2.2 Use
Security methods (passwords) 3. Testing
3.1 Determine Frequency 3.2 Create Test
packs 3.3 Document 4. Rejected Product
4.1 Isolate screen 4.2 Repeat 3 times
/ change orientation 4.3 Investigate
trained personnel / off line 4.4 Identify
potential source resolve 5. Maintain
Records 5.1 Test / Production / Maintenance