Why is it important to demagnetize engine parts after they have been inspected by magnetic particle methods?

• A. They will attract steel particles that are produced by engine wear and will cause damage to bearing surfaces.
• B. It shortens inspection time.
• C. It prevents rust on bearing surfaces.
• D. It improves sensitivity of the test.

Answer: (A)

After magnetic particle inspection, Parts hold a residual magnetic field. That lingering magnetism will attract ferrous particles, including steel particles produced by engine wear or iron filings in the surrounding environment. If these particles are drawn to bearing surfaces or journals, they can become abrasive and cause scoring or wear once the engine runs. Demagnetizing removes the residual magnetism, so those particles are no longer attracted to the part, reducing the risk of debris causing damage during operation and future handling or assembly. The other statements don’t fit because demagnetizing after inspection doesn’t shorten the inspection time, isn’t primarily about rust prevention, and doesn’t increase the test’s sensitivity—the test’s sensitivity comes from the magnetizing step itself.