M8 is one of the standard coarse-thread sizes for phillips pan head self-tapping screw under GB/T 845 / ISO 7049. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M8 Dimensional Row (GB/T 845 / ISO 7049)
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Cross recess | Reference standard |
|---|---|---|---|---|---|---|
| M8 | 1.25 | 50 | 16.0 | 4.8 | PH3 | ISO 7045 / GB/T 818 |
Spanner & Drive for M8 Phillips Pan Head Self-Tapping Screw — GB/T 845 / ISO 7049 (Series 032)
M8 Phillips Pan Head Self-Tapping Screw — GB/T 845 / ISO 7049 (Series 032) use a PH3 cross recess. Match the driver bit to the recess (Phillips PH / Pozi PZ are NOT interchangeable).
Hole Sizes for M8
| Coarse-thread pitch (ISO 724) | 1.25 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 9 mm |
| Tapping drill, coarse thread | 6.8 mm |
Tightening Torque for M8
| Class 8.8 (dry, ~µ 0.125) | ≈ 25 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 35 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 41 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.
Proof Load & Strength for M8
| Tensile stress area As (ISO 898-1) | 36.6 mm² |
|---|---|
| Proof load, class 8.8 | 21 kN |
| Proof load, class 10.9 | 30 kN |
| Proof load, class 12.9 | 36 kN |
| Min. ultimate tensile, class 8.8 | 29 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
M8 Phillips Pan Head Self-Tapping Screw — GB/T 845 / ISO 7049 (Series 032) Weight
A steel M8 phillips pan head self-tapping screw at the listed 50 mm length weighs approximately 79 g each — about 79 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³). Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Common Applications for M8 Phillips Pan Head Self-Tapping Screw — GB/T 845 / ISO 7049 (Series 032)
M8 Phillips Pan Head Self-Tapping Screw — GB/T 845 / ISO 7049 (Series 032) are commonly specified for machine assembly, general engineering, plant maintenance and OEM equipment.
Installation Tips for M8 Phillips Pan Head Self-Tapping Screw — GB/T 845 / ISO 7049 (Series 032)
- Pozidriv (PZ) drivers ride out of Phillips (PH) recesses and vice versa — confirm the recess marking on the head before assembly.
- For automated assembly, an ACR (Anti-Cam-Out Ribs) or torx-equivalent driver gives noticeably longer bit life than plain PH.
Mating Parts for M8
For M8, pair with a M8 hex nut (ISO 4032 / DIN 934) and, where used, a M8 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.