M18 Grade 5.6 Torque Specification

Torque Values by Surface Condition

Stress area: 192.47 mm² · Proof load: 53,892 N · Clamp load (75%): 40,419 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	145.5	107.3	1287.8	1483.7
Oiled	0.15	109.1	80.5	965.6	1112.5
Zinc Plated	0.18	131.0	96.6	1159.4	1335.8
Waxed	0.1	72.8	53.7	644.3	742.4
MoS₂	0.12	87.3	64.4	772.7	890.2
Galvanized	0.25	181.9	134.2	1610.0	1854.9

Stress area: 216.23 mm² · Proof load: 60,544 N · Clamp load (75%): 45,408 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	163.5	120.6	1447.1	1667.2
Oiled	0.15	122.6	90.4	1085.1	1250.2
Zinc Plated	0.18	147.1	108.5	1301.9	1500.0
Waxed	0.1	81.7	60.3	723.1	833.1
MoS₂	0.12	98.1	72.4	868.3	1000.3
Galvanized	0.25	204.3	150.7	1808.2	2083.3

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 280 MPa × 192.47 mm² = 40,419 N

Step 2 — Torque (dry): T = 0.20 × 0.0180 m × 40,419 N = 145.5 N·m

Proof stress per ISO 898-1:2013 Table 4. Stress area per ISO 898-1 Annex A. K-factor per VDI 2230.

Moderate-duty industrial applications, machinery guards, medium-strength connections

• Torque values are for standard hex bolts with ISO metric threads. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard (e.g., VDI 2230).
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

SizeM18

Class5.6

Diameter18 mm

Pitch (coarse)2.5 mm

Tensile500 MPa

Yield300 MPa

Proof280 MPa