The Mechanical
Engineering Handbook




Surface Roughness Chart



Iso Grade Number Ra (μm) Ra (μin.)
N12 50 2000
N11 25 1000
N10 12.5 500
N9 6.3 250
N8 3.2 125
N7 1.6 63
N6 0.8 32
N5 0.4 16
N4 0.2 8
N3 0.1 4
N2 0.05 2
N1 0.025 1

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