M7 Grade 6.8 Torque Specification

Torque Values by Surface Condition

Stress area: 28.86 mm² · Proof load: 12,698 N · Clamp load (75%): 9,524 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	13.3	9.8	117.7	135.6
Oiled	0.15	10.0	7.4	88.5	102.0
Zinc Plated	0.18	12.0	8.9	106.2	122.4
Waxed	0.1	6.7	4.9	59.3	68.3
MoS₂	0.12	8.0	5.9	70.8	81.6
Galvanized	0.25	16.7	12.3	147.8	170.3

Stress area: 31.23 mm² · Proof load: 13,741 N · Clamp load (75%): 10,306 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	14.4	10.6	127.5	146.8
Oiled	0.15	10.8	8.0	95.6	110.1
Zinc Plated	0.18	13.0	9.6	115.1	132.6
Waxed	0.1	7.2	5.3	63.7	73.4
MoS₂	0.12	8.7	6.4	77.0	88.7
Galvanized	0.25	18.0	13.3	159.3	183.5

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 440 MPa × 28.86 mm² = 9,524 N

Step 2 — Torque (dry): T = 0.20 × 0.0070 m × 9,524 N = 13.3 N·m

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

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.

SizeM7

Class6.8

Diameter7 mm

Pitch (coarse)1.0 mm

Tensile600 MPa

Yield480 MPa

Proof440 MPa