Surface Topography

Definition - What does Surface Topography mean?

Surface topography is the local deviations of a surface from a perfectly flat plane.

The topography of a surface is known to substantially affect the bulk properties of a material. Despite the often nanoscale nature of surface irregularities, the influence they have may be observed by macroscopic measurements.

The characterization of surface topography has become increasingly important in many fields, such as materials, tribology and machine condition monitoring.

Surface topography also known as surface texture or surface finish.

Corrosionpedia explains Surface Topography

Surface topography is the nature of a surface as defined by the three characteristics:

  • Lay - The direction of the predominant surface pattern ordinarily determined by the production method used
  • Surface roughness - Closely spaced irregularities (cutting tool marks, grit of grinding wheel). In engineering, this is what is usually meant by "surface finish."
  • Waviness - More widely spaced irregularities (vibration and chatter). These usually occur due to warping, vibrations or deflection during machining.

Surface topography is an important factor that controls friction and transfer layer formation during sliding. Surface topography can be either isotropic or anisotropic. Sometimes, stick-slip friction phenomena can be observed during sliding depending on surface topography.

Each manufacturing process produces a surface topography. Many factors contribute to the surface topography in manufacturing. In general, the cost of manufacturing a surface increases as the surface finish becomes smoother.

Due to the abstractness of surface topography parameters, engineers usually use a tool that has a variety of surface roughnesses created using different manufacturing methods. The process is usually optimized to ensure that the resulting texture is usable.

Surface topography may be measured in two ways:

  • Contact methods - Involve dragging a measurement stylus (profilometer) across the surface
  • Non-contact methods - Including:
    • Interferometry
    • Confocal microscopy
    • Focus variation
    • Structured light
    • Electrical capacitance
    • Electron microscopy
    • Photogrammetry

The most common method is to use a diamond stylus profilometer. The stylus is run perpendicular to the lay of the surface.

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