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Surface roughness

Surface roughness is generally the degree of texture variability of a surface. In metrology, surface roughness measures the amount of bumps and dents, or peaks and valleys, across the surface of a part. These irregularities are to be expected on any machined surface provided the natural result of working with a range of tools to cut, shape, and build a part. The peaks and valleys, in other words the degree of surface roughness, are important in the eventual functionality of a part. Manufacturers will often measure surface roughness using a surface roughness gage or tester, and get a parameter in the form of Average Roughness (Ra) or Mean Roughness Depth (Rz). While these are the most common parameters used, other measures of surface roughness exist.
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