M56 Grade 5.6 Torque Specification

Torque Values by Surface Condition

Stress area: 2030.0 mm² · Proof load: 568,400 N · Clamp load (75%): 426,300 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4774.6	3521.6	42258.8	48687.6
Oiled	0.15	3580.9	2641.1	31693.7	36515.2
Zinc Plated	0.18	4297.1	3169.4	38032.6	43818.4
Waxed	0.1	2387.3	1760.8	21129.4	24343.8
MoS₂	0.12	2864.7	2112.9	25354.7	29211.9
Galvanized	0.25	5968.2	4401.9	52823.0	60858.9

Stress area: 2120.0 mm² · Proof load: 593,600 N · Clamp load (75%): 445,200 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4986.2	3677.6	44131.6	50845.3
Oiled	0.15	3739.7	2758.3	33099.1	38134.5
Zinc Plated	0.18	4487.6	3309.9	39718.6	45761.0
Waxed	0.1	2493.1	1838.8	22065.8	25422.6
MoS₂	0.12	2991.7	2206.6	26478.8	30507.0
Galvanized	0.25	6232.8	4597.1	55165.0	63557.1

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 280 MPa × 2030.0 mm² = 426,300 N

Step 2 — Torque (dry): T = 0.20 × 0.0560 m × 426,300 N = 4774.6 N·m

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

Moderate-duty industrial applications, machinery guards, medium-strength connections

• 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.

SizeM56

Class5.6

Diameter56 mm

Pitch (coarse)5.5 mm

Tensile500 MPa

Yield300 MPa

Proof280 MPa