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SURFACE ROUGHNESS

PARAMETERS

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Surface Roughness tester

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Master specimen - Calibration

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Ra - Mean Roughness / Roughness Average

  • Ra is the arithmetic average of the absolute values of the roughness profile ordinates.
  • Ra is one of the most effective surface roughness measures commonly adopted in

General engineering practice.

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Rq / RMS- Root mean square roughness

  • RMS is calculated by measuring the height of a surfaces microscopic peaks and

valleys, squaring those measurements

  •  RMS is defined as the square root of the mean square  

(The arithmetic mean of the squares of a set of numbers).

  • This value is typically 11% higher than Ra value

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Rz – Average maximum height of the profile

  •  The vertical distance between the highest and lowest points of the profile within

a sampling length.  

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Rt –Maximum height of the profile

  • Total height of profile is the vertical distance between the maximum profile peak

height and the maximum profile valley depth along the evaluation length.