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Magnetic Particle Inspection of Odd Shaped Parts

Many components in the automotive and engineering industry have shapes that are difficult to test with conventional magnetic particle inspection machines.

These parts are difficult to load on the standard magnetic particle test benches and do not follow the current requirements given in ASTM standards.

These parts also need to be magnetized in two directions perpendicular to each other.

In order to magnetize these parts, we have developed a double-head machine, wherein two pairs of head & tail tocks perpendicular to each other are used to magnetize the part.

The field generated by both pairs is circular in nature, but the two fields are perpendicular to each other.

Calculation of headshot current is done as per the formula given in ASTM standards.

Head Shot Current = 20 X Diameter (in mm)

In the above formula, the diameter should be taken as the maximum distance between any two points along the length of the part.

A tailor-made bench-type machine is used to perform magnetic particle testing on such parts. The part is placed on the machine by using specially designed fixtures. A pneumatically operated arrangement is used to clamp the part from all four ends. Pneumatic clamping ensures that there is no sparking when a high current is passed through the part. The use of braided copper pads is also recommended to eliminate arcing sparks.


Multidirectional magnetization is a special technique employed to identify defects in all orientations within a single examination. This stands in contrast to the combined magnetization shot utilized in traditional machines, which doesn’t align with ASTM standards. This technique proves effective in identifying both longitudinal and transverse cracks within one examination.

In this machine, multidirectional magnetization is used so that defects in all directions can be detected in one shot.

Testing Procedure for conventional machines

  • Clean up & dry the part’s surface before inspecting.
  • The part is placed on the fixture.
  • Now apply a magnetic solution bath to the part.
  • Press the ‘Cycle Start’ button.
  • The part automatically gets clamped from all sides.
  • Stop the flow of the bath.
  • Now, the current passes through the part in multidirectional mode.
  • It shows up on the digital metering unit.
  • The part automatically gets de-clamped.
  • Inspect the front surface of the part under UV light for all defects.
  • Take out the part & place it on the grills.
  • Inspect the back surface of the part under UV light for all defects.
  • Demagnetize

suitable products

Standard MPI Machines

Engineered for precision and efficiency, the Standard Bench Type Magnetic Particle Testing Machine is suitable for entry level testing.

PLC Controlled MPI Bench

With PLC Controlled bench type Magnetic Particle Inspection Machine, you can accurately control the process parameters for reilable results.

Multidirectional MPI Bench

The ultimate solution for robust non-destructive testing, this machine offers multi-directional magnetization for inspection in all directions in one shot..


Demagnetizers stand as a key tool in maintaining excellence in production, with the flexibility to handle different materials and magnetism levels, coupled with energy-efficient and user-friendly design.



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