ISO 7040 is the international standard for nylon insert hex lock nut — gb/t 889 / iso 7040 (series 078). This page sets out what the standard governs, the size range it specifies, and the related standards you will see referenced in datasheets.
ISO 7040 — Scope
ISO 7040 specifies the dimensions and tolerances of nylon insert hex lock nut — gb/t 889 / iso 7040 (series 078). 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 GB/T 889 / 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 (mm) | Total height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 4.0 | ISO 7040 / DIN 985 |
| M4 | 0.7 | 7.0 | 7.66 | 5.0 | ISO 7040 / DIN 985 |
| M5 | 0.8 | 8.0 | 8.79 | 5.0 | ISO 7040 / DIN 985 |
| M6 | 1.0 | 10.0 | 11.05 | 6.0 | ISO 7040 / DIN 985 |
| M8 | 1.25 | 13.0 | 14.38 | 8.0 | ISO 7040 / DIN 985 |
| M10 | 1.5 | 16.0 | 17.77 | 10.0 | ISO 7040 / DIN 985 |
| M12 | 1.75 | 18.0 | 20.03 | 12.0 | ISO 7040 / DIN 985 |
| M14 | 2.0 | 21.0 | 23.36 | 14.0 | ISO 7040 / DIN 985 |
| M16 | 2.0 | 24.0 | 26.75 | 16.0 | ISO 7040 / DIN 985 |
| M18 | 2.5 | 27.0 | 30.14 | 18.0 | ISO 7040 / DIN 985 |
| M20 | 2.5 | 30.0 | 33.53 | 20.0 | ISO 7040 / DIN 985 |
| M24 | 3.0 | 36.0 | 39.98 | 22.0 | ISO 7040 / DIN 985 |
| M30 | 3.5 | 46.0 | 50.85 | 25.0 | ISO 7040 / DIN 985 |
| M36 | 4.0 | 55.0 | 60.79 | 29.0 | ISO 7040 / DIN 985 |
Companion Standards
ISO 7040 controls only the geometry of nylon insert hex lock nut — gb/t 889 / iso 7040 (series 078). The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).
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 nylon insert hex lock nut — gb/t 889 / iso 7040 (series 078).