Specification summary of ISO 7040 as applied to nyloc lock nuts: the dimensions the standard controls, the tolerance and product grades it defines, the full specified size range, and the equivalent DIN/ISO/ASME designations.
ISO 7040 — Scope
ISO 7040 specifies the dimensions and tolerances of nyloc lock nuts. Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).
Tolerance & Product Grades
ISO 7040, alongside the related DIN 985 / ISO 7040 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.
Dimensions Specified by ISO 7040
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Total height m (mm) | Metal height (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 4.0 | 2.4 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M4 | 0.7 | 7.0 | 7.66 | 5.0 | 3.2 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M5 | 0.8 | 8.0 | 8.79 | 5.0 | 3.7 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M6 | 1.0 | 10.0 | 11.05 | 6.0 | 4.7 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M8 | 1.25 | 13.0 | 14.38 | 8.0 | 6.14 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M10 | 1.5 | 16.0 | 17.77 | 10.0 | 8.04 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M12 | 1.75 | 18.0 | 20.03 | 12.0 | 9.64 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M14 | 2.0 | 21.0 | 23.36 | 14.0 | 11.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M16 | 2.0 | 24.0 | 26.75 | 16.0 | 13.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M20 | 2.5 | 30.0 | 32.95 | 20.0 | 16.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M24 | 3.0 | 36.0 | 39.55 | 22.0 | 19.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M30 | 3.5 | 46.0 | 50.85 | 25.0 | 24.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M36 | 4.0 | 55.0 | 60.79 | 29.0 | 29.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Nyloc Lock Nuts page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify ISO 7040
Choose ISO 7040 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for nyloc lock nuts.
