For hexalobular socket head cap screws, ISO 14579 fixes the geometry and the tolerances. The sections below describe the scope of the document, the properties it deliberately leaves to companion standards, and the equivalent designations across standards bodies.
ISO 14579 — Scope
ISO 14579 is "Hexalobular socket head cap screws". The hexalobular-drive counterpart of ISO 4762.
Material, property class, surface finish and packaging are governed by separate documents — ISO 898-1 and ISO 898-2 for mechanical property classes, ISO 4042 for electroplated finishes.
Tolerance & Product Grades
ISO 14579 does not divide hexalobular socket head cap screws into product grades. Tolerances are given as limits on the individual dimensions in the table.
Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by ISO 14579
| Size | Drive size | A (mm) | t_mean (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|
| M2 | T6 | 1.75 | 0.8 | 3~20 | ISO 14579 |
| M2.5 | T8 | 2.4 | 1.0 | 4~25 | ISO 14579 |
| M3 | T10 | 2.8 | 1.2 | 5~30 | ISO 14579 |
| M4 | T20 | 3.95 | 1.7 | 6~40 | ISO 14579 |
| M5 | T25 | 4.5 | 1.9 | 8~50 | ISO 14579 |
| M6 | T30 | 5.6 | 2.3 | 10~60 | ISO 14579 |
| M8 | T45 | 7.95 | 3.2 | 12~80 | ISO 14579 |
| M10 | T50 | 8.95 | 3.8 | 16~100 | ISO 14579 |
| M12 | T55 | 11.35 | 5.0 | 20~120 | ISO 14579 |
| (M14) | T60 | 13.45 | 5.8 | 25~140 | ISO 14579 |
| M16 | T70 | 15.7 | 6.8 | 25~160 | ISO 14579 |
| (M18) | T80 | 17.75 | 7.8 | 30~180 | ISO 14579 |
| M20 | T90 | 20.2 | 9.0 | 30~200 | ISO 14579 |
Companion Standards
ISO 14579 controls only the geometry of hexalobular socket head cap screws. The mechanical strength is set by ISO 898-1 (bolts, screws and studs) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards such as ISO 4042 for electroplating. For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).
When to Specify ISO 14579
Choose ISO 14579 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for hexalobular socket head cap screws.
Custom manufacturing · Made to drawing
Need a screw to this standard in a non-standard size?
Parts built to ISO 14579 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
