COPPER PADS – FULL DESCRIPTION

Copper Pads (also called Copper Contact Pads or Copper Shims) are thin copper plates used in Magnetic Particle Testing (MT/MPI) to provide a clean, uniform, and safe contact surface when applying prod technique or direct contact magnetization.

They prevent arcing, protect the test piece from burn marks, and help ensure proper current flow into the part.

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✔ Purpose of Copper Pads in MPI

Copper Pads are primarily used to:

• Prevent electrical arcing during prod-type magnetization

• Protect the component surface from scorch marks

• Provide good electrical conductivity

• Ensure uniform current distribution

• Avoid damage to coated or finished surfaces

• Assist in achieving reliable magnetic fields during testing

They are essential whenever prod MPI is used on sensitive or finished parts.

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✔ Construction

Copper Pads are typically:

• Made from high-conductivity copper

• Thickness: 1–3 mm

• Shape:

  • Square

  • Rectangular

  • Round (for curved surfaces)

• Often come with:
  ✔ Smooth edges
  ✔ Textured or grooved surface for better grip
  ✔ Insulated backing (sometimes)

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✔ Working Principle

During MPI using prods, high electrical current (AC, HWDC) is passed between two prod tips placed on the surface.

Placing Copper Pads under the prods:

• Increases contact area

• Reduces current density at a single point

• Prevents melting or burning of the base metal

• Ensures smooth current flow

• Helps create consistent magnetic fields

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✔ When Copper Pads Are Used

Copper Pads are essential in:

• Prod magnetization technique

• Testing thin plates

• Components with painted / coated surfaces

• Sensitive materials that may burn

• High-current MPI applications (above 300–600 A)

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✔ How to Use Copper Pads (Step-by-Step)

1. Clean the test surface.

2. Place a copper pad under each prod tip.

3. Press the prod firmly to ensure good contact.

4. Apply magnetization current.

5. Apply magnetic particles and observe indications.

6. Move pads if multiple locations are tested.

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✔ Advantages

• Prevents arc burns and damage

• Provides reliable electrical contact

• Extends life of prod tips

• Ensures consistent magnetization

• Suitable for field and workshop use

• Safe for coated, plated, or machined surfaces

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✔ Limitations

• Must be cleaned regularly

• Wear out over time and need replacement

• Cannot eliminate arcing if prod pressure is too low

• Not useful in non-contact MPI methods (yoke or coil)

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✔ Applications

Used in:

• Magnetic Particle Testing (Prod Method)

• Weld inspection

• Structural steel testing

• Heavy fabrication work

• Pipelines, plates, and large components

• High-current MPI bench units (when direct contact is used)

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If you want, I can also provide:

📌 ALT image description of Copper Pads
📌 Short catalog description
📌 Prod Technique step-by-step procedure
📌 Advantages vs. Aluminum Pads

Just tell me!