M12 is one of the standard coarse-thread sizes for spring lock washer under GB/T 5782 / ISO 4014. 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 5782 / ISO 4014)
| For bolt size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Width b (mm) | Thickness t (mm) | Reference standard |
|---|---|---|---|---|---|
| M12 | 12.2 | 21.1 | 3.5 | 3.0 | GB/T 93 / DIN 127B |
Spanner & Drive for M12 Spring Lock Washer — GB/T 5782 / ISO 4014 (Series 003)
Drive geometry for M12 Spring Lock Washer — GB/T 5782 / ISO 4014 (Series 003) is given by the row above; match the tool to the listed values.
Common Applications for M12 Spring Lock Washer — GB/T 5782 / ISO 4014 (Series 003)
M12 Spring Lock Washer — GB/T 5782 / ISO 4014 (Series 003) are commonly specified for medium-duty structural joints.
Mating Parts for M12
A M12 flat washer pairs with a M12 bolt/screw and matching M12 nut.
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.