NovaTork Torque Tools Catalog (Europe) 2025_EuG01 - Flipbook - Sida 84
Torque Knowledge
What is
TORQUE
Torque Unit
Bolt
& Torque
The torque is equal to the arm of force (L) multiply the applied force (F).
E.g. F = 100N, L = 2m, then T = 100×2 = 200 N • m
T=F•L
L
T — Torque
F
T
F — Applied force
L — Arm of force
F — N (Newton), Lb (Pound), Kg (Kilogram)
L — m (Meter), cm (Centimeter), ft (Foot), in (Inch)
T — N.m (Newton meter), cN.m (Newton centimeter), Lb.ft (Foot-pound)
Lb.in (Inch-pound), Kg.m (Kilogram-meter), cKg.m (Kilogram-centimeter)
Strength of bolt ↑, and Torque ↑;
Bolt surface friction coefficient ↑,
and Torque ↑;
Bolt threads friction coefficient ↑,
and Torque ↑;
Bolt specification ↑, and Torque ↑.
Bolt surface
friction
coefficient
50%
Axial
compression
torque 10%
Bolt threads
friction
coefficient
40%
The approximate percentage of torque
acting on the bolt:
Bolt Grade
& Mark
Torque
Bolt grade is marked as below:
X • Y
10 Times yield ratio
Separator
1/100 Tensile strength
（Yield ratio =
Yield strength
）
Tensile strength
E.g. Bolt grade 4.6, means:
(1) Tensile strength of bolt material is
400MPa
(2) Yield ratio of bolt material is 0.6
(3) Bolt yield strength is 400×0.6 =
240MPa
Bolt grade 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9, etc.
High strength bolt’s grade is above 8.8, others are called common bolt.
8.8
Bolt grade mark:
8.8
8.8
8.8
Hex Bolt
Torque Unit
Conversion
Allen Bolt
N·m
kg·m
Lb·ft
Lb·in
1 N·m =
1
0.101972
0.737562
8.850744
1 kg·m =
9.80665
1
7.23301
86.79612
1 Lb·ft =
1.35582
0.138255
1
12
1 Lb·in =
0.112985
0.011521
0.083333
1
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