Non-destructive testing is not one technique but a toolbox, and each tool answers a different question. Magnetic Particle Testing (MT) reveals surface and near-surface discontinuities in ferromagnetic materials — it is highly sensitive to the fatigue and grinding cracks that matter on crankshafts and shafts, but it only works on magnetic materials. Liquid Penetrant Testing (PT) finds surface-breaking flaws in almost any non-porous material, including stainless and non-ferrous alloys, but cannot see below the surface.
Visual Testing (VT) is the baseline on every inspection program, and Ultrasonic Testing (UT) reaches volumetric, sub-surface defects and can measure thickness. Each adds coverage the others cannot provide — which is exactly why method selection matters more than method count.
The right choice depends on the material, the component geometry, the defect mechanism you are actually looking for, and the access available in the field. A method used outside its limits produces false confidence, which on a critical crankshaft is worse than no inspection at all.
OSM International currently performs MT and PT under our employer ASNT SNT-TC-1A written practice, and we are candid about what each method can and cannot detect. Where a component needs coverage a method cannot provide, we say so rather than overstate the result.
Updated 2026-07-10