Surface Roughness Converter & Texture Reference Tool
Surface Roughness & Texture Reference Tool
ISO Parameter Conversion · Profile Viewer · Drawing Symbols · Manufacturing Guide
Input Parameter
ISO Roughness Grade (N-Scale)
Active Grade:
N7
(Ra =
1.6 μm
)
Default Sampling Length — ISO 4288
λc =0.8 mm
ln =4.0 mm
λs =0.0025 mm
n =5 (default)
λc: sampling length (long-wave cut-off) · ln: evaluation length (5×λc) · λs: short-wave filter
Converted Values
Ra
Arithmetical Mean Deviation
Average |Z(x)| over sampling length
1.60μm
Rz
Maximum Height of Profile
Rp + Rv within one sampling length
9.60μm
Rq
RMS Deviation
≈ 1.11 × Ra (Gaussian surface)
1.78μm
Rt
Total Height of Profile
Rp + Rv over evaluation length ln
14.4μm
Rp
Max Profile Peak Height
Largest Zp above mean line
4.80μm
Rv
Max Profile Valley Depth
Largest Zv below mean line
4.80μm
Ra
μin / CLA (Imperial)
Ra in micro-inches
63μin
N
N7
ISO Roughness Grade
N1–N12 per ISO 1302:2002
Default λc = 0.8 mm
ISO 4288 — Tolerance Interpretation Rules
16%-Rule (default)
Without “max” suffix (e.g.
Ra 1.6): up to 16% of all measured values may exceed the limit. This is the default per ISO 4288:1996 §5.2.Max-Rule
With “max” suffix (e.g.
Ra max 1.6): no single measured value may exceed the limit. For critical functional surfaces. ISO 4288:1996 §5.3.Surface Profile Simulation — ISO 4287:1997
Ra · Mean deviation
1.600 μm
Rz · Max height
6.400 μm
Rq · RMS deviation
1.776 μm
How to Read a Surface Profile
Mean line (dashed blue)Reference line from which all deviations Z(x) are measured. Ra = average of all absolute distances from this line.
Sampling length (λc)Basic length over which profile is assessed. ISO 4288 specifies default λc by Ra range. 5 sections shown = evaluation length ln.
Rz markers (orange)Tallest peak (Rp) + deepest valley (Rv) within the first sampling length λ1. Rz = Rp + Rv. Varies section to section.
Evaluation length ln = 5×λcRt uses the worst peak+valley across ALL 5 sections, so Rt ≥ Rz always.
ISO 1302:2002 — Symbol Builder
Surface Lay Symbols — ISO 1302:2002, Table 2
| Symbol | Interpretation |
|---|---|
| = | Lay parallel to the plane of projection of the view in which the symbol is used |
| ⊥ | Lay perpendicular to the plane of projection |
| X | Lay crossed in two oblique directions relative to the plane of projection |
| M | Multi-directional |
| C | Approximately circular relative to the centre of the surface |
| R | Approximately radial relative to the centre of the surface |
| P | Lay is particulate, non-directional, or protuberant |
Symbol Preview
aMain surface texture requirement
b2nd texture requirement (below a)
cManufacturing method / coating
dSurface lay direction
eMachining allowance (mm)
ISO 1302:2002 — Figure 4 & Figure 6
Manufacturing Processes — Typical Ra Ranges & Rz/Ra Factors
Typical Ra ranges and Rz/Ra ratios. Values are indicative; actual results depend on machine condition, feeds, speeds, tool geometry, and workpiece material.
| Process | Ra Range (μm) | Ra Range (μin) | Rz/Ra | N-Grade Range | Range Bar |
|---|
ISO Roughness Grade (N-Scale) — ISO 1302:2002 Annex I, Table I.2
| N Grade | Ra (μm) | Ra (μin) | Rz ≈ ×6 (μm) | λc (mm) | ln (mm) |
|---|
ISO 4287:1997 — Surface Profile Parameter Reference
Parameters defined in ISO 4287:1997 (BS EN ISO 4287:1998+A1:2009). First letter: R=roughness, W=waviness, P=primary profile. Same definitions apply to all three profiles.
§4.1 — Amplitude Parameters (Peak and Valley)
| Symbol | Name | Definition (ISO 4287:1997) | Formula |
|---|---|---|---|
| Rp/Wp/Pp | Maximum profile peak height | Largest profile peak height Zp within a sampling length lr | max(Zp) in lr |
| Rv/Wv/Pv | Maximum profile valley depth | Largest profile valley depth Zv within a sampling length lr | max(Zv) in lr |
| Rz/Wz/Pz | Maximum height of profile | Rp + Rv within ONE sampling length. Formerly called Ry. Old ten-point Rz no longer ISO-standardized. | Rz = Rp + Rv |
| Rc/Wc/Pc | Mean height of profile elements | Mean value of all profile element heights Zt within sampling length | Rc=(1/m)·ΣZtᵢ |
| Rt/Wt/Pt | Total height of profile | Largest Zp + Zv over EVALUATION LENGTH ln. Rt ≥ Rz always. | Rt over ln |
§4.2 — Amplitude Parameters (Average of Ordinates)
| Symbol | Name | Definition | Formula |
|---|---|---|---|
| Ra/Wa/Pa | Arithmetical mean deviation | Mean of |Z(x)| within sampling length. Most used parameter globally. | Ra=(1/l)·∫|Z(x)|dx |
| Rq/Wq/Pq | Root mean square deviation | RMS of Z(x) within sampling length. Rq ≈ 1.11×Ra for Gaussian surface. | Rq=√(1/l·∫Z²dx) |
| Rsk/Wsk/Psk | Skewness of profile | Mean cube of Z(x) / Rq³. Asymmetry: Rsk<0 = more valleys; Rsk>0 = more peaks. | Rsk=(1/Rq³)·(1/l·∫Z³dx) |
| Rku/Wku/Pku | Kurtosis of profile | Mean 4th power of Z(x) / Rq⁴. Sharpness of height distribution. Gaussian ≈ 3. | Rku=(1/Rq⁴)·(1/l·∫Z⁴dx) |
§4.3 — Spacing Parameters
| Symbol | Name | Definition | Note |
|---|---|---|---|
| RSm/WSm/PSm | Mean width of profile elements | Mean of all profile element widths Xs within sampling length. Needs height AND spacing discrimination. | RSm=(1/m)·ΣXsᵢ |
| RPc/WPc/PPc | Peak count number (§4.3.2) | L / RSm in reference length L (default 10 mm). Height discrimination ±0.5 μm recommended. | RPc = L / RSm |
§4.4 — Hybrid Parameters
| Symbol | Name | Definition | Formula |
|---|---|---|---|
| RΔq/WΔq/PΔq | Root mean square slope | RMS of ordinate slopes dZ/dX within sampling length. Strongly depends on ordinate spacing ΔX. | RΔq=√(1/l·∫(dZ/dX)²dx) |
§4.5 — Curves and Related Parameters (Abbott-Firestone)
| Symbol | Name | Definition | Note |
|---|---|---|---|
| Rmr(c) | Material ratio of the profile | Ml(c)/ln — ratio of material length at section level c to evaluation length. Defines Abbott-Firestone curve. | Rmr(c)=Ml(c)/ln |
| Rδc | Profile section height difference | Vertical distance between two section levels of given material ratio on the Abbott-Firestone curve. | Rδc=C(Rmr1)−C(Rmr2) |
| Rmr | Relative material ratio | Material ratio at level Rδc relative to reference C0. Used for plateau honing analysis (ISO 13565-2/3). | Abbott-Firestone analysis |
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