5/ Surface imperfections
Code 5/ limits scratches, digs and other surface imperfections. It is written in the field of the surface it applies to. 15/ is used for imperfections in an optical assembly.
Standard: ISO 10110-7:2017
Syntax
| 5/N×A | N = number of allowed imperfections, A = grade number = square root of the max. imperfection area, in mm. |
| ; C N×A | Coating imperfections (count × grade). Without it, coating blemishes count toward the general imperfections. |
| ; L N×A | Long scratches (> 2 mm): count × max. width in mm. |
| ; W A | Max. width of any imperfection in mm; not combined with L. |
| ; E A | Edge chips: any number allowed if none extends more than A mm from the physical edge. |
| 5/S-D | Visibility method (2017 edition), analogous to MIL scratch-dig; the comparison standard must be named on the drawing. |
Worked examples
| 5/ 3x0.16; L2x0.004; E0.5 | Up to 3 imperfections of grade 0.16 (max. area 0.0256 mm² each, total ≤ 0.0768 mm²); up to 2 long scratches ≤ 0.004 mm wide; edge chips may extend up to 0.5 mm from the edge. |
| 5/ 2x0.1; C3x0.16 | Up to 2 imperfections of grade 0.1, plus up to 3 coating imperfections of grade 0.16. |
| 5/ 60-40; E0.5 | Visibility method: scratch 60, dig 40, plus edge chips ≤ 0.5 mm. |
Click an example to open it in the decoder.
Common values and typical grades
| Grades | 4, 2.5, 1.6, 1.0, 0.63, 0.4, 0.25, 0.16, 0.1, 0.063, 0.04, 0.025, 0.016, 0.01 (R5 series) |
| Long-scratch widths | 0.1, 0.063, 0.04, 0.025, 0.016, 0.01, 0.006, 0.004 mm |
| ≈ MIL 60-40 (20 mm part) | 5/ 2×0.40; L3×0.010 |
| ≈ MIL 40-20 | 5/ 2×0.16; L2×0.010 |
| ≈ MIL 20-10 | 5/ 2×0.10; L2×0.006 |
| ≈ MIL 10-5 | 5/ 2×0.04; L2×0.004 |
The MIL equivalents are approximate equal-yield values from ISO/TR 21477 for a 20 mm part; visibility and dimensional grades are not directly convertible verify.
Common mistakes
- Reading 0.16 as a scratch width or dig diameter. It is the square root of an area: 0.16 → 0.0256 mm².
- Writing MIL “60-40” as if it were the dimensional method. Use
5/60-40(visibility) and name the comparison standard, or convert. - Combining W and L in one callout.
- Forgetting E: without it, edge chips may not extend into the optically effective area.
Questions
What does 5/ 3x0.16 mean?
Up to 3 surface imperfections of grade 0.16, i.e. each with an area of at most 0.0256 mm²; smaller ones are summed against the total 3 × 0.16² = 0.0768 mm² (ISO 10110-7).
What does L2x0.004 mean?
Up to 2 long scratches (longer than 2 mm), each no wider than 0.004 mm.
What does E0.5 mean?
Edge chips are allowed in any number as long as none extends more than 0.5 mm from the physical edge.
Can I use 60-40 scratch-dig in ISO 10110?
Yes, ISO 10110-7:2017 has a visibility method written 5/60-40; the comparison standard must be named on the drawing. It is not directly convertible to the dimensional method.
Sources
ISO 10110-7:2017; ISO/TR 21477 equivalents as cited in the literature. Full list and edition status: Sources & editions.
An unofficial summary written from public previews of the standards and reputable secondary sources. It does not reproduce the ISO text. Items marked verify could not be fully confirmed. Check against the current edition; see Sources & editions.