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Evaluation parameters of surface roughness
Mar 16, 2018

1. Highly characteristic parameters.

Ra contour arithmetic mean deviation: the arithmetic mean of the absolute value of the offset in the sampling length (lr). In the actual measurement, the more the measuring points, the more accurate the Ra.

The maximum height of the Rz contour: the distance between the top line and the valley bottom line.

Ra is preferred in the range of range parameters. Before 2006 in the national standard and an evaluation parameter for microscopic asperity height "ten" expressed with Rz, outline of the maximum height with Ry, said in 2006 after the national standard of cancelled the microscopic roughness height of ten, adopting Rz said maximum height.

2. Spacing characteristic parameters.

Average width of the Rsm contour unit. In the sample length, the average of the contour interval of the contour. The microscopic irregularity interval is the length of the contour peak and the adjacent contour valley on the middle line. In the case of the same Ra value, the Rsm value is not necessarily the same, so the texture reflected will be different, and the surface of the texture will usually focus on the Ra and Rsm.

The Rmr shape characteristic parameter is indicated by the contour support length ratio, which is the ratio of contour support length to sample length. The contour support length is the sum of the length of each section of the line that is parallel to the middle line and the contour of the contour line is the length of the sampling length.

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