Why is adherence of magnetic particles to defects important in testing?

The adherence of magnetic particles to defects is crucial in testing because it directly affects the accuracy of the indication of those defects. When magnetic particles are applied to a ferromagnetic surface, they will cluster or accumulate at areas where there are discontinuities or flaws, such as cracks and voids. This clustering creates a visible indication that can be easily identified during inspection.

The ability of the particles to adhere to these defects is what makes Magnetic Particle Testing effective. Without this adherence, the particles would not form a clear, distinguishable signal over the flaw, making it difficult or impossible to detect the issue being inspected. Therefore, accurate detection hinges on the efficient accumulation of the particles at the defect site, allowing for a reliable assessment of the structural integrity of the material being tested. This means that the presence of a defect can be visualized clearly, enabling inspectors to make informed decisions concerning repairs or further evaluation.