M12 is one of the standard coarse-thread sizes for castellated hex nut under GB/T 6180 / ISO 7036. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M12 Dimensional Row (GB/T 6180 / ISO 7036)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Total height m (mm) | Slot width (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M12 | 1.75 | 18.0 | 20.03 | 15.8 | 3.5 | ISO 7036 / GB/T 6180 |
Spanner & Drive for M12 Castellated Hex Nut — GB/T 6180 / ISO 7036 (Series 048)
Drive geometry for M12 Castellated Hex Nut — GB/T 6180 / ISO 7036 (Series 048) is given by the row above; match the tool to the listed values.
Common Applications for M12 Castellated Hex Nut — GB/T 6180 / ISO 7036 (Series 048)
M12 Castellated Hex Nut — GB/T 6180 / ISO 7036 (Series 048) are commonly specified for medium-duty structural joints and motor / chassis mounting.
Mating Parts for M12
Pair M12 with the matching M12 bolt or screw, plus a M12 flat washer where required to distribute load on softer materials.
When to Step Up or Down from M12
When the joint preload approaches the proof load of M12 class 8.8, step up to M16 class 8.8 (or move to M12 class 10.9). When the joint is over-specified, M10 often saves weight and cost without losing the safety margin.