Pinnatarkkuus

Pinnatarkkuus refers to the precision of a surface's form and finish. It encompasses both the geometrical accuracy of a surface, such as its flatness, straightness, or roundness, and the characteristics of the surface texture, like roughness and waviness. Achieving high pinnatarkkuus is crucial in many manufacturing and engineering applications where precise interactions between components are required.

The geometrical accuracy of a surface is measured against an ideal form. Deviations from this ideal are quantified and controlled. For example, in bearings, the roundness of the shaft and the bore is critical for smooth operation and longevity. Similarly, in optical applications, the flatness of a mirror surface must be extremely high to ensure accurate reflection of light.

Surface texture, on the other hand, describes the finer details of a surface. Roughness refers to the small-scale irregularities, typically resulting from the manufacturing process like grinding or polishing. Waviness describes larger-scale deviations in the surface profile. The degree of surface texture is often measured using parameters such as Ra (average roughness) or Rz (maximum height of the profile).

The required level of pinnatarkkuus depends heavily on the intended function of the part. Components that require tight sealing, low friction, or high optical performance will demand much higher pinnatarkkuus than, for instance, a structural element where only load-bearing capacity is important. Manufacturing processes and measurement techniques are specifically designed to achieve and verify these precise surface characteristics.