ISO 4027 is the standard cited for engineered component. This page sets out what the standard controls for this part, reproduces the dimensional table supplied against it, and notes the related designations referenced on drawings.
ISO 4027 — Scope
ISO 4027 specifies the dimensional requirements for engineered component — gb/t 78 / iso 4027 (series 026). Material, surface condition and any performance rating are set by separate documents specific to this part family — ISO 898-1 and ISO 898-2, which govern bolt and nut property classes, do not apply here.
Tolerance & Product Grades
Tolerances for engineered component — gb/t 78 / iso 4027 (series 026) are given as limits on the individual dimensions in the table rather than as a fastener product grade. Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by ISO 4027
| Size designation | Outer diameter / width (mm) | Length / height (mm) | Bore / thread (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| Size 1 | 10 | 20 | 6 | C45 carbon steel | GB/T 1804-m |
| Size 2 | 12 | 25 | 8 | C45 carbon steel | GB/T 1804-m |
| Size 3 | 16 | 32 | 10 | C45 carbon steel | GB/T 1804-m |
| Size 4 | 20 | 40 | 12 | C45 carbon steel | GB/T 1804-m |
| Size 5 | 25 | 50 | 16 | C45 carbon steel | GB/T 1804-m |
| Size 6 | 32 | 63 | 20 | C45 carbon steel | GB/T 1804-m |
| Size 7 | 40 | 80 | 25 | C45 carbon steel | GB/T 1804-m |
| Size 8 | 50 | 100 | 30 | C45 carbon steel | GB/T 1804-m |
Companion Standards
ISO 4027 controls only the geometry of engineered component — gb/t 78 / iso 4027 (series 026). Surface finish is governed by separate finish standards (for example ISO 4042 for electroplating), and corrosion testing by ISO 9227 (neutral salt spray). Mechanical performance is set by the standards specific to this part family, not by ISO 898-1 or ISO 898-2, which apply to bolts, screws and nuts.
When to Specify ISO 4027
Choose ISO 4027 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for engineered component — gb/t 78 / iso 4027 (series 026).
