The strength of materials are given by the microstructure and structure flaws of the material. Machined components are strength influenced by residual stresses and microcracks in the subsurface due to the process. Grinding processes lead to longitudinal, radial, and lateral surface cracks. For material strength, longitudinal and radial cracks are important because of the stress concentration of these notch effects.

The detection of cracks and flaws by dye penetration technique, non-destructive optical, or scanning electronic microscopically methods are not suitable for ceramics because of the size of the microcracks. Only macro-cracks can be detected with these methods