Surface Roughness Chart
Browse N grade, Ra, Rz, Rmax, and Rt reference values.
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Surface Roughness Chart
| N | Ra (μm) | Rz (μm) | Rmax (μm) | Rt (μm) |
|---|---|---|---|---|
| N1 | 0.025 | 0.1 | 0.16 | 0.18 |
| N2 | 0.05 | 0.2 | 0.32 | 0.36 |
| N3 | 0.1 | 0.4 | 0.63 | 0.72 |
| N4 | 0.2 | 0.8 | 1.25 | 1.44 |
| N5 | 0.4 | 1.6 | 2.5 | 2.88 |
| N6 | 0.8 | 3.2 | 5 | 5.76 |
| N7 | 1.6 | 6.3 | 10 | 11.5 |
| N8 | 3.2 | 12.5 | 20 | 23 |
| N9 | 6.3 | 25 | 40 | 46 |
| N10 | 12.5 | 50 | 80 | 92 |
| N11 | 25 | 100 | 160 | 184 |
| N12 | 50 | 200 | 320 | 368 |
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Purpose
The chart is a fast alignment tool. Use it when design, programming, quality, and suppliers need a shared picture of what a finish requirement means in practice. A visual range often prevents arguments that come from numbers being copied without context.
Recommended workflow
- Confirm the actual part target, tool condition, and controller constraints first.
- Use the tool to build a reviewable baseline, not an unverified production extreme.
- Compare the output with machine limits, holder clearance, finish targets, and restart logic.
- After prove-out, tune one variable at a time and store the accepted rule with revision context.
How to interpret the result
This tool is most valuable when it helps the team answer three questions: Is the target clear? Is the process controllable? Can the result be repeated across shifts and machines? Whether the output is a chart, an estimate, or a program skeleton, it should be read together with machine capability, inspection method, tooling condition, and recovery expectations. That is what turns a convenient calculation into a usable production baseline.
Common risks and checks
A chart should guide expectation, not replace metrology. Always connect the visual reference back to the actual standard, measurement direction, cutoff, and instrument method. Otherwise the chart looks persuasive while process decisions still drift.
When the result disagrees with the shop floor, check units, defaults, controller assumptions, tool condition, and recovery steps before questioning the core math. Teams get the best value when they feed the prove-out result back into setup notes, revision logs, and shift handoff documents.
Visual reference
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Final recommendation
Put the tool inside a fixed engineering loop: establish a baseline, validate the first piece, tune one variable at a time, and freeze the accepted rule with context. That approach delivers repeatability instead of one-off numbers.
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Related Terms
Surface Roughness
Measure of microscopic surface irregularity.
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