M18 is one of the standard coarse-thread sizes for thin hex castle nut under GB/T 6181 / ISO 4035. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M18 Dimensional Row (GB/T 6181 / ISO 4035)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Total height m (mm) | Slot width (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M18 | 2.5 | 27.0 | 30.14 | 22.5 | 4.5 | ISO 7036 / GB/T 6180 |
Spanner & Drive for M18 Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053)
Drive geometry for M18 Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053) is given by the row above; match the tool to the listed values.
Common Applications for M18 Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053)
M18 Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053) are commonly specified for structural joints, flange connections and heavy equipment foundations.
Installation Tips for M18 Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053)
- At M18 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
Mating Parts for M18
Pair M18 with the matching M18 bolt or screw, plus a M18 flat washer where required to distribute load on softer materials.