ISO 14579 M2.5
Socket head cap screw,hexalobular (Torx) drive
- Thread M2.5 × 0.45
- Torx bit T8
- Tap drill Ø 2.05 mm
Dimensions and tolerances (mm)
| min | nom. | max | |
|---|---|---|---|
| d | |||
| dk | |||
| k | |||
| T | |||
| A | |||
| t |
Values per ISO 14579:2011.
In bold: the value shown in the table on the standard page.
Design and assembly (mm)
- Tap drillDIN 336, coarse thread
- Ø 2.05
- Clearance holeISO 273, dh by fit
- close Ø 2.7normal Ø 2.9loose Ø 3.1
Mechanical properties
Preload and torque for: medium clearance hole (ISO 273), tightening to ν = 90 % of yield, coarse thread, µG = µK = 0.14.
| Property class | Loads, ISO 898-1 | Tightening, VDI 2230 | Calculator | ||
|---|---|---|---|---|---|
| ProofkN | BreakkN | PreloadkN | TorqueN·m | ||
| Steel 8.8Steel 8.8 Tensile strength Rm ≥ 800 MPa, yield Rp0.2 ≥ 640 MPa (80 % of Rm). The everyday property class for machine parts. | Property class 8.8 does not cover M2.5. | ||||
| Steel 10.9Steel 10.9 Tensile strength Rm ≥ 1040 MPa, yield Rp0.2 ≥ 940 MPa (90 % of Rm). High strength, for heavily loaded joints. | Property class 10.9 does not cover M2.5. | ||||
| Steel 12.9Steel 12.9 Tensile strength Rm ≥ 1220 MPa, yield Rp0.2 ≥ 1100 MPa (90 % of Rm). The strongest property class in common use. Sensitive to hydrogen: avoid electroplated coatings. The property class this standard is usually made in.usual | Property class 12.9 does not cover M2.5. | ||||
| Stainless A2-70Stainless A2-70 Tensile strength Rm ≥ 700 MPa, yield Rp0.2 ≥ 450 MPa. Austenitic stainless A2 (like AISI 304): general corrosion resistance. | Property class A2-70 does not cover M2.5. | ||||
| Stainless A4-80Stainless A4-80 Tensile strength Rm ≥ 800 MPa, yield Rp0.2 ≥ 600 MPa. Austenitic stainless A4 (like AISI 316, with molybdenum): for sea water and chemicals. | Property class A4-80 does not cover M2.5. | ||||
* Stainless: load at yield (Rp0.2 × As); ISO 3506-1 gives no proof load.
Stainless steel: the real friction is higher and scatters widely, so the torque shown is only a starting point; type your own µ in the box.
- Stress area As
- 3.4 mm²
- Shank area A
- 4.9 mm²
Standard threads (mm)
| P | d₂ | d₃ | |
|---|---|---|---|
| M2.5Coarse (most common) | 0.45 | 2.208 | 1.948 |
Profile per ISO 68-1 · tolerance class 6g
Standard lengths (mm)
Length l measured from under the head.
Screws up to about 17 mm are fully threaded.Longer ones are threaded for b = 17 mm.
Verified data
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References
- ISO 14579:2011 Hexalobular socket head cap screws
- ISO 68-1:1998 ISO general purpose screw threads — Basic profile — Part 1: Metric screw threads
- ISO 898-1:2013 Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws and studs
- ISO 3506-1:2020 Fasteners — Mechanical properties of corrosion-resistant stainless steel fasteners — Part 1: Bolts, screws and studs
- VDI 2230 Part 1:2015 Systematic calculation of highly stressed bolted joints — Joints with one cylindrical bolt
- DIN 336:2003 Diameters of drills for minor diameters of tapped threads
- ISO 273:1979 Fasteners — Clearance holes for bolts and screws