M48 Grade 5.6 Torque Specification

Torque Values by Surface Condition

Stress area: 1473.19 mm² · Proof load: 412,493 N · Clamp load (75%): 309,370 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2970.0	2190.6	26286.7	30285.7
Oiled	0.15	2227.5	1642.9	19715.0	22714.3
Zinc Plated	0.18	2673.0	1971.5	23658.1	27257.1
Waxed	0.1	1485.0	1095.3	13143.4	15142.8
MoS₂	0.12	1782.0	1314.3	15772.0	18171.4
Galvanized	0.25	3712.4	2738.1	32857.5	37856.1

Stress area: 1602.9 mm² · Proof load: 448,812 N · Clamp load (75%): 336,609 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3231.4	2383.4	28600.3	32951.2
Oiled	0.15	2423.6	1787.6	21450.7	24713.9
Zinc Plated	0.18	2908.3	2145.1	25740.6	29656.5
Waxed	0.1	1615.7	1191.7	14300.2	16475.6
MoS₂	0.12	1938.9	1430.1	17160.7	19771.4
Galvanized	0.25	4039.3	2979.2	35750.8	41189.5

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 280 MPa × 1473.19 mm² = 309,370 N

Step 2 — Torque (dry): T = 0.20 × 0.0480 m × 309,370 N = 2970.0 N·m

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

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.

SizeM48

Class5.6

Diameter48 mm

Pitch (coarse)5.0 mm

Tensile500 MPa

Yield300 MPa

Proof280 MPa