ISO 4026 covers the dimensional requirements for hex socket flat point set screw. Reproduced below: the complete size table, the tolerance grades, and the companion and equivalent standards referenced when ordering to this document.
ISO 4026 — Scope
ISO 4026 specifies the dimensions and tolerances of hex socket flat point set screw — gb/t 77 / iso 4026 (series 021). 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 4026, alongside the related GB/T 77 / ISO 4026 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 4026
| Size | Pitch (mm) | Length L (mm) | Hex socket s (mm) | Engagement depth t min (mm) | Point diameter dp (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 6 | 1.5 | 1.4 | 2.0 | ISO 4026-4029 / GB/T 77-79 |
| M4 | 0.7 | 6 | 2.0 | 2.0 | 2.5 | ISO 4026-4029 / GB/T 77-79 |
| M5 | 0.8 | 7 | 2.5 | 2.5 | 3.5 | ISO 4026-4029 / GB/T 77-79 |
| M6 | 1.0 | 9 | 3.0 | 3.0 | 4.0 | ISO 4026-4029 / GB/T 77-79 |
| M8 | 1.25 | 12 | 4.0 | 4.0 | 5.5 | ISO 4026-4029 / GB/T 77-79 |
| M10 | 1.5 | 15 | 5.0 | 5.0 | 7.0 | ISO 4026-4029 / GB/T 77-79 |
| M12 | 1.75 | 18 | 6.0 | 6.0 | 8.5 | ISO 4026-4029 / GB/T 77-79 |
| M16 | 2.0 | 24 | 8.0 | 8.0 | 12.0 | ISO 4026-4029 / GB/T 77-79 |
| M20 | 2.5 | 30 | 10.0 | 10.0 | 15.0 | ISO 4026-4029 / GB/T 77-79 |
| M24 | 3.0 | 36 | 12.0 | 12.0 | 18.0 | ISO 4026-4029 / GB/T 77-79 |
Companion Standards
ISO 4026 controls only the geometry of hex socket flat point set screw — gb/t 77 / iso 4026 (series 021). 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 4026
Choose ISO 4026 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for hex socket flat point set screw — gb/t 77 / iso 4026 (series 021).