M24 Grade 6.8 Torque Specification

Torque Values by Surface Condition

Stress area: 352.5 mm² · Proof load: 155,100 N · Clamp load (75%): 116,325 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	558.4	411.9	4942.3	5694.1
Oiled	0.15	418.8	308.9	3706.7	4270.6
Zinc Plated	0.18	502.5	370.6	4447.5	5124.1
Waxed	0.1	279.2	205.9	2471.1	2847.1
MoS₂	0.12	335.0	247.1	2965.0	3416.1
Galvanized	0.25	698.0	514.8	6177.8	7117.6

Stress area: 384.42 mm² · Proof load: 169,145 N · Clamp load (75%): 126,859 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	608.9	449.1	5389.2	6209.1
Oiled	0.15	456.7	336.8	4042.1	4657.1
Zinc Plated	0.18	548.0	404.2	4850.2	5588.1
Waxed	0.1	304.5	224.6	2695.1	3105.0
MoS₂	0.12	365.4	269.5	3234.1	3726.1
Galvanized	0.25	761.2	561.4	6737.2	7762.1

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 440 MPa × 352.5 mm² = 116,325 N

Step 2 — Torque (dry): T = 0.20 × 0.0240 m × 116,325 N = 558.4 N·m

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

Industrial machinery, agricultural equipment, elevated load requirements

• 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.

SizeM24

Class6.8

Diameter24 mm

Pitch (coarse)3.0 mm

Tensile600 MPa

Yield480 MPa

Proof440 MPa