M64 Grade 4.8 Torque Specification

Torque Values by Surface Condition

Stress area: 2676.0 mm² · Proof load: 829,560 N · Clamp load (75%): 622,170 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	7963.8	5873.8	70485.6	81208.5
Oiled	0.15	5972.8	4405.3	52863.8	60905.8
Zinc Plated	0.18	7167.4	5286.4	63436.9	73087.4
Waxed	0.1	3981.9	2936.9	35242.8	40604.2
MoS₂	0.12	4778.3	3524.3	42291.5	48725.3
Galvanized	0.25	9954.7	7342.2	88106.6	101510.1

Stress area: 2809.0 mm² · Proof load: 870,790 N · Clamp load (75%): 653,092 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	8359.6	6165.7	73988.7	85244.5
Oiled	0.15	6269.7	4624.3	55491.5	63933.4
Zinc Plated	0.18	7523.6	5549.1	66589.5	76719.7
Waxed	0.1	4179.8	3082.9	36994.4	42622.3
MoS₂	0.12	5015.8	3699.5	44393.6	51147.1
Galvanized	0.25	10449.5	7707.2	92485.9	106555.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 310 MPa × 2676.0 mm² = 622,170 N

Step 2 — Torque (dry): T = 0.20 × 0.0640 m × 622,170 N = 7963.8 N·m

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

Light structural connections, furniture assembly, non-load-bearing joints

• 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.

SizeM64

Class4.8

Diameter64 mm

Pitch (coarse)6.0 mm

Tensile420 MPa

Yield340 MPa

Proof310 MPa