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Surface finish measurement

Surface texture

In general, the term "surface texture" refers to the primary profile, roughness, waviness and other surface attributes such as the direction of the surface features (also referred to as the "lay" of the surface).
Surface finish - characteristics

Surface finish

Surface finish - terms

Mainly refers to the "roughness" aspect of the surface. 

Procedures needed to calculate surface roughness

  • Remove the underlying geometry shape
  • Separate out the waviness and roughness
  • Calculate surface roughness

Remove underlying geometry shape

Surface finish - geometry removed

Separate the waviness and roughness

Filtering surface profiles involves running a "smoothing" filter through the primary data. Shorter wavelengths fall into the roughness profile and longer wavelengths appear in the waviness profile.

Seperate the waviness

Calculate roughness

  • Ra – Average roughness
  • Rv– Maximum valley depth
  • Rp– Maximum peak depth
  • Rt– Maximum height of profile
  • Rz– Average peak-to-valley roughness
Rt surface roughness 

Filter

  • Gaussian filter (ASME and ISO recommended ISO 11562-1992, ISO/TS 16610-21)
Surface finish measurement data filter

Measurement

  • Stylus (skidded and skidless)
Surface finish measurement