The M3 size of Slotted Pan Head Screw is dimensioned by GB/T 67 / ISO 1580. The tables below give the dimensional row from the standard, the drill and spanner sizes that go with it, and the assembly torque per property class. The technical drawing on this page redraws to the exact values selected.
M3 Dimensional Row (GB/T 67 / ISO 1580)
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Cross recess | Reference standard |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 20 | 5.6 | 1.8 | PH1 | ISO 7045 / GB/T 818 |
Spanner & Drive for M3 Slotted Pan Head Screw — GB/T 67 / ISO 1580 (Series 040)
M3 Slotted Pan Head Screw — GB/T 67 / ISO 1580 (Series 040) use a PH1 cross recess. Match the driver bit to the recess (Phillips PH / Pozi PZ are NOT interchangeable).
Hole Sizes for M3
| Coarse-thread pitch (ISO 724) | 0.5 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 3.4 mm |
| Tapping drill, coarse thread | 2.5 mm |
Tightening Torque for M3
| Class 8.8 (dry, ~µ 0.125) | ≈ 1.3 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 2.2 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 M3
| Tensile stress area As (ISO 724) | 5 mm² |
|---|---|
| Proof load, class 8.8 | 2.9 kN |
| Proof load, class 12.9 | 4.9 kN |
| Min. ultimate tensile load, class 8.8 | 4 kN |
Proof load = tensile stress area × the proof stress Sp of the class, per ISO 898-1 — Sp is a lower figure than the yield stress Rp0.2 and the two are not interchangeable. The stress area is computed from this size's own diameter and pitch, so a fine-pitch designation gives the fine-pitch figure. Design the joint so the working preload stays below the proof load of the class selected.
M3 Slotted Pan Head Screw — GB/T 67 / ISO 1580 (Series 040) Weight
A steel M3 slotted pan head screw at the listed 20 mm length weighs approximately 3.9 g each — about 3.9 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.
Installation Tips for M3 Slotted Pan Head Screw — GB/T 67 / ISO 1580 (Series 040)
- 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.
- At M3 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
When to Step Up or Down from M3
When the joint preload approaches the proof load of M3 class 8.8, step up to M4 class 8.8 (or move to M3 class 10.9). When the joint is over-specified, M2 often saves weight and cost without losing the safety margin.
Custom manufacturing · Made to drawing
Need slotted pan head screw in a size this table does not list?
This page covers M3 slotted pan head screw. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
