When you need Heavy Hex Socket Head Cap Screw — GB/T 1228 / ASTM A325 (Series 046) in the M5 size, the controlling values come from GB/T 1228 / ASTM A325. This page lists them in one place — pitch, head geometry, tool size and the matching hole.
M5 Dimensional Row (GB/T 1228 / ASTM A325)
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Hex socket s (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M5 | 0.8 | 30 | 8.5 | 5 | 4.0 | ISO 4762 / GB/T 70.1 |
Spanner & Drive for M5 Heavy Hex Socket Head Cap Screw — GB/T 1228 / ASTM A325 (Series 046)
The hex socket for M5 Heavy Hex Socket Head Cap Screw — GB/T 1228 / ASTM A325 (Series 046) 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 M5
| Coarse-thread pitch (ISO 724) | 0.8 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 5.5 mm |
| Tapping drill, coarse thread | 4.2 mm |
Tightening Torque for M5
| Class 8.8 (dry, ~µ 0.125) | ≈ 5.8 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 8.1 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 9.7 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 M5 Heavy Hex Socket Head Cap Screw — GB/T 1228 / ASTM A325 (Series 046)
M5 Heavy Hex Socket Head Cap Screw — GB/T 1228 / ASTM A325 (Series 046) are commonly specified for electronics, PCB hardware, optical mounts and small-scale machinery.
Mating Parts for M5
For M5, pair with a M5 hex nut (ISO 4032 / DIN 934) and, where used, a M5 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M5
When the joint preload approaches the proof load of M5 class 8.8, step up to M6 class 8.8 (or move to M5 class 10.9). When the joint is over-specified, M4 often saves weight and cost without losing the safety margin.