M64 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 2676.0 mm² · Proof load: 1,016,880 N · Clamp load (75%): 762,660 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	9762.0	7200.1	86401.0	99545.1
Oiled	0.15	7321.5	5400.1	64800.8	74658.8
Zinc Plated	0.18	8785.8	6480.1	77760.9	89590.6
Waxed	0.1	4881.0	3600.0	43200.5	49772.5
MoS₂	0.12	5857.2	4320.0	51840.6	59727.0
Galvanized	0.25	12202.6	9000.2	108002.2	124432.4

Stress area: 2809.0 mm² · Proof load: 1,067,420 N · Clamp load (75%): 800,565 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	10247.2	7557.9	90695.4	104492.7
Oiled	0.15	7685.4	5668.5	68021.6	78369.6
Zinc Plated	0.18	9222.5	6802.2	81626.0	94043.7
Waxed	0.1	5123.6	3779.0	45347.7	52246.4
MoS₂	0.12	6148.3	4534.8	54417.1	62695.4
Galvanized	0.25	12809.0	9447.4	113369.3	130615.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 2676.0 mm² = 762,660 N

Step 2 — Torque (dry): T = 0.20 × 0.0640 m × 762,660 N = 9762.0 N·m

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

General industrial fastening, equipment mounting, moderate structural loads

• 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

Class5.8

Diameter64 mm

Pitch (coarse)6.0 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa