When you need Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039) in the M6 size, the controlling values come from GB/T 68 / ISO 2009. This page lists them in one place — pitch, head geometry, tool size and the matching hole.
M6 Dimensional Row (GB/T 68 / ISO 2009)
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Cross recess | Countersink angle (deg) | Reference standard |
|---|---|---|---|---|---|---|---|
| M6 | 1.0 | 40 | 11.0 | 3.0 | PH3 | 90 | ISO 7046 / GB/T 819 |
Spanner & Drive for M6 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039)
The hex socket for M6 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039) is shown in the spec table — use the matching Allen / hex key (an ISO 2936 hex key set covers the full range). A T-handle Allen key gives the best feel for setting preload by feel; for production work use a torque-controlled driver.
Hole Sizes for M6
| Coarse-thread pitch (ISO 724) | 1 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 6.6 mm |
| Tapping drill, coarse thread | 5 mm |
Tightening Torque for M6
| Class 8.8 (dry, ~µ 0.125) | ≈ 10 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 14 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 17 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 M6 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039)
M6 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039) are commonly specified for machine assembly, general engineering, plant maintenance and OEM equipment.
Mating Parts for M6
For M6, pair with a M6 hex nut (ISO 4032 / DIN 934) and, where used, a M6 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M6
When the joint preload approaches the proof load of M6 class 8.8, step up to M8 class 8.8 (or move to M6 class 10.9). When the joint is over-specified, M5 often saves weight and cost without losing the safety margin.