For Hex Head Bolt, Fully Threaded — GB/T 5783 / ISO 4017 (Series 012), the M12 thread sits in the medium range of the catalog and is one of the most-asked hex head bolt, fully threaded — gb/t 5783 / iso 4017 (series 012) in this family. The dimensional and assembly data follow.
M12 Dimensional Row (GB/T 5783 / ISO 4017)
| Size | Pitch (mm) | Nominal diameter d (mm) | Length L (mm) | Width across flats s (mm) | Width across corners e (mm) | Head height k (mm) |
|---|---|---|---|---|---|---|
| M12 | 1.75 | 12 | 80 | 18.0 | 20.03 | 7.5 |
Spanner & Drive for M12 Hex Head Bolt, Fully Threaded — GB/T 5783 / ISO 4017 (Series 012)
M12 Hex Head Bolt, Fully Threaded — GB/T 5783 / ISO 4017 (Series 012) have a width across flats of 18.0 mm — fit a 18.0 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Hole Sizes for M12
| Coarse-thread pitch (ISO 724) | 1.75 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 13.5 mm |
| Tapping drill, coarse thread | 10.2 mm |
Tightening Torque for M12
| Class 8.8 (dry, ~µ 0.125) | ≈ 85 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 120 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 145 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Common Applications for M12 Hex Head Bolt, Fully Threaded — GB/T 5783 / ISO 4017 (Series 012)
M12 Hex Head Bolt, Fully Threaded — GB/T 5783 / ISO 4017 (Series 012) are commonly specified for medium-duty structural connections, automotive sub-frames and equipment chassis.
Installation Tips for M12 Hex Head Bolt, Fully Threaded — GB/T 5783 / ISO 4017 (Series 012)
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
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.