M42 Grade 5.6 Torque Specification

Torque Values by Surface Condition

Stress area: 1120.9 mm² · Proof load: 313,852 N · Clamp load (75%): 235,389 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1977.3	1458.4	17500.6	20162.9
Oiled	0.15	1483.0	1093.8	13125.7	15122.4
Zinc Plated	0.18	1779.5	1312.5	15749.9	18145.9
Waxed	0.1	988.6	729.2	8749.9	10081.0
MoS₂	0.12	1186.4	875.0	10500.5	12098.0
Galvanized	0.25	2471.6	1823.0	21875.5	25203.4

Stress area: 1205.7 mm² · Proof load: 337,596 N · Clamp load (75%): 253,197 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2126.9	1568.7	18824.7	21688.4
Oiled	0.15	1595.1	1176.5	14117.8	16265.6
Zinc Plated	0.18	1914.2	1411.8	16942.1	19519.5
Waxed	0.1	1063.4	784.3	9411.9	10843.7
MoS₂	0.12	1276.1	941.2	11294.4	13012.6
Galvanized	0.25	2658.6	1960.9	23530.6	27110.3

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 280 MPa × 1120.9 mm² = 235,389 N

Step 2 — Torque (dry): T = 0.20 × 0.0420 m × 235,389 N = 1977.3 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.

SizeM42

Class5.6

Diameter42 mm

Pitch (coarse)4.5 mm

Tensile500 MPa

Yield300 MPa

Proof280 MPa