M20 Grade 5.6 Torque Specification

Torque Values by Surface Condition

Stress area: 244.79 mm² · Proof load: 68,541 N · Clamp load (75%): 51,406 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	205.6	151.6	1819.7	2096.5
Oiled	0.15	154.2	113.7	1364.8	1572.4
Zinc Plated	0.18	185.1	136.5	1638.3	1887.5
Waxed	0.1	102.8	75.8	909.9	1048.3
MoS₂	0.12	123.4	91.0	1092.2	1258.3
Galvanized	0.25	257.0	189.6	2274.6	2620.7

Stress area: 271.5 mm² · Proof load: 76,020 N · Clamp load (75%): 57,015 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	228.1	168.2	2018.9	2326.0
Oiled	0.15	171.0	126.1	1513.5	1743.7
Zinc Plated	0.18	205.3	151.4	1817.1	2093.5
Waxed	0.1	114.0	84.1	1009.0	1162.5
MoS₂	0.12	136.8	100.9	1210.8	1395.0
Galvanized	0.25	285.1	210.3	2523.3	2907.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 280 MPa × 244.79 mm² = 51,406 N

Step 2 — Torque (dry): T = 0.20 × 0.0200 m × 51,406 N = 205.6 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.

SizeM20

Class5.6

Diameter20 mm

Pitch (coarse)2.5 mm

Tensile500 MPa

Yield300 MPa

Proof280 MPa