M36 Grade 6.8 Torque Specification

Torque Values by Surface Condition

Stress area: 816.72 mm² · Proof load: 359,357 N · Clamp load (75%): 269,518 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1940.5	1431.2	17174.9	19787.7
Oiled	0.15	1455.4	1073.4	12881.4	14841.0
Zinc Plated	0.18	1746.5	1288.2	15457.8	17809.4
Waxed	0.1	970.3	715.7	8587.9	9894.3
MoS₂	0.12	1164.3	858.7	10304.9	11872.6
Galvanized	0.25	2425.7	1789.1	21469.3	24735.3

Stress area: 864.95 mm² · Proof load: 380,578 N · Clamp load (75%): 285,434 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2055.1	1515.8	18189.2	20956.3
Oiled	0.15	1541.3	1136.8	13641.7	15716.9
Zinc Plated	0.18	1849.6	1364.2	16370.3	18860.7
Waxed	0.1	1027.6	757.9	9095.0	10478.6
MoS₂	0.12	1233.1	909.5	10913.9	12574.2
Galvanized	0.25	2568.9	1894.7	22736.7	26195.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 440 MPa × 816.72 mm² = 269,518 N

Step 2 — Torque (dry): T = 0.20 × 0.0360 m × 269,518 N = 1940.5 N·m

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

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.

SizeM36

Class6.8

Diameter36 mm

Pitch (coarse)4.0 mm

Tensile600 MPa

Yield480 MPa

Proof440 MPa