Factors Affecting
Tightening Torque
The tightening torque is affected by
a wide variety of factors including the
following. After tightening, always check
the torque with a torque wrench.
1) Voltage
When the battery pack becomes nearly
discharged, the voltage decreases and
the tightening torque drops.
Bolt Tightening Conditions
Tightening time (Sec.)
M10, M12, M14, M16 Standard bolt
Tightening torque
N • m
(kgf-cm)
Tightening time (Sec.)
M8, M10, M12, M14 High tensile bolt
Tightening torque
N • m
(kgf-cm)
Bolt
Nut
Washer
Steel plate
thickness 10 mm (3/8")
Washer
Spring washer
Tightening conditions
* The following bolts are used.
Standard bolts: Strength type 6.8
High tensile type 12.9
Explanation of the strength type
Bolt yield point
(80% of tensile strength)
48 kgf/mm
2
(68000 psi)
Bolt tensile strength 60 kgf/mm
2
(85000 psi)
2) Tightening time
Longer tightening time results in
increased tightening torque. Excessive
tightening, however, adds no value and
reduces the life of the tool.
3) Different bolt diameters
The size of the bolt diameter affects the
tightening torque.
Generally, as the bolt diameter
increases, tightening torque rises.
(EY7271 only)
(EY7271 only)
